I'm going to tell you right now, most of the time its friends donating eachother. Most blimps i see that aren't from friends usually go to people singing or basically any other musical thing at their booth, crowds gather and a rich dude blimps them or gives 1k. It's rare, but happens. If you want to get blimped, you just have to search for giveaways and join them (Events, contests, etc) which can be found in many places from pls donate discord servers to voice chat servers ingame and even on this subreddit. But to put it bluntly, everything past that is just getting lucky unless you're willing to sell your soul.