Whales. People with huge amounts of disposable income. People who spend a lot. People who have a giant size portfolio. Etc. It's a term I've seen used in a number of different context but always eluding to someone with a ton of money.

Im guessing Web cams / Chat Rooms.

Like twitch you can spend money to have your donation read / request fulfilled.

One time I saw a sex toy that automatically updated the setting to the highest bidders request so there would be a tug of war between those increasing and lowering the setting. Definitely a great revenue stream if you are savvy.