Why do exchanges gamble with customers’ money?

As the title says, I was always wondering. If you’re big fish on the market, why are you risking your reputation and financial stability in hopes for crazy returns? We have seen what FTX did, and some other exchanges as well, but don’t they make a lot from the fees already? Someone clear this up for me please.

P.S: Did you know that if you hold the space bar, your cursor will move? Truly a very helpful feature to make our lives easier. I discovered this few weeks ago and it truly helped me a lot in daily routines on the internet such as chatting on this subreddit.