That's the rough part with acquiring characters (or anything) through the equivalent of cash-funded roulette: you can set out to spend a certain amount to attain something you want, but it might not work, and if you're sufficiently unlucky it may turn into an order of magnitude more spending than you originally intended.
While you could of course commit to only spending $X and dealing with the results even if they're unsatisfactory, this can be surprisingly difficult psychologically, combining the best of the gambler's fallacy with the sunk cost fallacy (among many other behaviors very cleverly inspired by the game's developers) into one.
Worse for me, as I'll likely ignore the pay route and go the exceedingly long and grindy route, and if I feel they've made that far too punishing for the rewards, I'll likely feel the game isn't rewarding enough to play. I'm not really interesting in proving to myself that I can pay money to do better than other people, so it doesn't help me enjoy games that are competitive in any way, and if it's a non-competitive game, I just feel like I'm being manipulated, which also saps the enjoyment out of it for me.
I don't mind purely cosmetic offerings being present in games, and I'll even buy a few. But if I feel like I'm competing on a field that's stratified by money, it just kills the enjoyment for me. It's the same reason I stopped playing Magic: The Gathering back in the mid nineties a few months after when it was first released. It was fun when we all had starter decks, but after friends started collecting special cards, I saw where I thought it was going an opted out. The realization just sapped a lot of the enjoyment out of the game for me.
I feel like that a lot, so called pay-to-win games (or perhaps pay-to-progress) aren't my thing either for similar reasons, even though I could afford them. I've played GI for a bit, but very casually (even more so as it doesn't run on Linux, so I've only played it on mobile myself), and as long as I am finding things I enjoy, for example the music, voice acting, and UX, I don't mind the game's profit model, but I definitely will end up playing less when/if I reach the point(s) to where I am increasingly penalized for not paying.
While you could of course commit to only spending $X and dealing with the results even if they're unsatisfactory, this can be surprisingly difficult psychologically, combining the best of the gambler's fallacy with the sunk cost fallacy (among many other behaviors very cleverly inspired by the game's developers) into one.