re: How many of you guys/gals day trade and have made it your career?

You’re giving much too much weight to the “tech” of the big firms. Their size means they must trade a certain way. Your size means you can trade however you want, for better of for worse.

Moderately successful means different things to different people. I do really well in my business. 25 year old me would kill for my day trading profits. Mid 40s me has a family and mortgage and needs to spend more time running my business. It’s not as black and white as you are suggesting.