I did a really scary thing a few days ago and went through my transaction history and counted how much money I'd spent on gachas... Thankfully most of it was from a little over a year ago where up until that point I was super invested in them (still am, but I know better than to show that with my wallet now). But the real kicker was when I was comparing my FGO luck to a friend who always saved for months, or even a whole year at one point, for the units he wanted, someone who
only spent money for the guaranteed SSR that happened twice a year, I found he had much better luck than I did, and it turns out that most of my investment came from trying to obtain a single unit rather than spending and having the 'luxury' of obtaining multiple at once. It's really weird because I can count on more than one occassion rolling a rare unit with a 'YOLO' roll, so really most of the money spent gave me a net negative gain and I should just roll on a whim more often.
I've been burnt by off-banner spooks in FEH too many times though to seriously consider spending money on it again, and I find that the pity rate increase for every failed roll is a textbook example of
gambler's fallacy. I think that this is an appropriate time to mention that please, if you ever even
think about spending money on gacha, make sure you have someone you trust keep you in line so you don't fall for the sparkly lights. I've seen too many people get caught up in their summoning fever and then later casually mention that they spent something ridiculous like $1000 on this single banner. It's alright to have a bit of fun every now and then, BUT STICK TO YOUR BUDGET!