When I've earned enough XP in Pathfinder or Tales of the Valiant, or Requisition Points in a Warhammer 40,000 Crusade, or victories in Mansions of Madness, I convert those game points into real-world currency. The only bank that takes game points in exchange for cash is me, but exchanging game points for cash is actually a great way to regulate my own cash flow. The exchange rate is admittedly extremely variable, but there's an important constant: By demanding game points for cash expenditure, I prove to myself that I'm using the stuff I buy. To pay for something new, I have to play with the stuff I've got.
I used to work in a prosumer audio store. There was a very specific kind of customer that would come in and announce that they were going to become a professional DJ (or musician, or producer, or similar), and insisted that we sell them everything. They'd buy the biggest mixing desk plus a few aux decks, amps, pre-amps, monitors, high-end turntables or a metric ton of synths, a rack, effect units, pedals, mics, and headphones. What did they actually need? A turntable and an amp.
I think it's relatively common to front-load on gear, whether it's prosumer audio or tabletop gaming supplies or technical gadgets. I don't think it's exactly tied to money, either. Some people do have too much money, so it's easy for them to front-load their purchases. And other people are reacting to formerly having no money, and then suddenly earning enough to have disposable income. But other people don't have much money, and manage to front-load on cheap or even $0 stuff.
There are probably lots of reasons we do it, but my theory is that it's based on uncertainty.
You know you want to start playing tabletop games, but you don't know yet what that means. Are you the type of person who can buy 1 board game and play and re-play it for 5 years, exclusive of any other game? Or are you the type of person who will play lots of different games, cycling through them with the seasons? And if you enjoy a game, will you want to play expansions? You'd better grab everything so you're prepared.
Or maybe you're getting started in roleplaying games and wargames. What books do you need? What about miniatures? Are your choices under-powered? Over-powered? You'd better buy everything so you're prepared.
I love the concept of a beginner box, when a company packages up a minimum viable collection of assets for you to get started with your new hobby. Give me some game tokens, some dice, a board, and a just-the-basics rulebook. Let me decide whether this is an activity I enjoy enough to invest more time and money into, or whether it's something I can safely sell on to somebody else after having tried once or twice.
When a game lacks a beginner box (or I decide the beginner box isn't really what I want), I try to construct a kind of beginner box for myself. I find the components that, when combined, form a minimum viable kit for the activity I want to try. When I finally started painting miniatures, I bought a starter box of miniature paints and tried it out on some cheap miniatures I already owned in board games. When I started wargaming, I bought some used miniatures on Trademe. And I didn't buy anything else until I could prove to myself that I enjoyed those hobbies.
The trigger to buy something new and better is usually just a vibe. It's the moment I look up from something I'm doing and notice that the clock has seemingly skipped a few hours, again for the twentieth day in a row. Then again, I've been making gaming videos on Youtube for about 2 years now, and I'm still using a consumer- level webcam, so this method is a little imprecise.
Recently, I've been playing Warhammer 40,000 Crusades, Dungeoneer tournaments, and Mansions of Madness scenarios in earnest. I've been playing these very methodically, recording scores and writing battle reports. Because of that, I have a clear record of how often I get use out of these game assets. I'm not so mechanical that I've set an exchange rate for hours of gaming to purchase of additional game assets, so I can't say exactly what a point of XP or RP or VP is worth in New Zealand Dollars. For Warhammer 40,000, it seems that 10 RP is roughly equivalent to $80 (a blister pack character model, or a box of infantry troops), but of course XP in Pathfinder gets delivered in chunks of 80 or 100 or more so it's probably something like 1000 XP is worth $100 (the price of a source book). Mansions of Madness is murkier, because when I run out of scenarios in one box, I might exchange my victories for a $10 DLC or for a $100 physical expansion.
It gets more complex. Sometimes the echange rate doesn't necessarily translate to money. When I noticed how often I was playing Ragadorn Ale-house Brawl, I finally decided to fashion an miniature tavern out of cardboard and popsicle sticks. It took time and effort and it meant I was crafting on a lever of [relative] complexity that I'd never attempted before. The result wasn't amazing to look at (although I do think it's quaint, at least) but it's made my gaming sessions with the game far more enjoyable than playing it with no terrain or approximated terrain.
When I saw how much play my Genestealer Cults were getting in my Warhammer 40,000 games, I decided I wanted to try some character models in the army. I don't think it even occurred to me to purchase the models. I had so many spare Genestealer Cults and generic soldier body parts lying around that it was trivial to build and paint miniatures to fill the character roles. As a bonus, all 5 of them were easily repurposed as a small Hybrid Metamorphs unit. It took time and effort to kitbash the characters together and then to paint them, but I spent some Requisition Points and got them done.
It can be tempting to "bribe" yourself into embracing a new hobby, but at least for me that doesn't work. My leisure time informs me of what I ought to invest in. When I see myself spending time and effort on an activity, I tend to take that as a sign that it's an activity I enjoy, whether or not I particularly identify with it or even realise it. I don't pay to play, but I do play and I'll put effort into maybe that fun.