Bumble has a low return rate and those ladies seem to be looking for relationships. But most on there are just browsing. My experience anyway.
So far as doubling down, I message until I get that unmatch (if I get the unmatch, typically just no reply). BUT not in one day, I'm talking over the course of weeks. I'll throw out the message, no response? Follow up with that gif a few days later. Nothing? Throw out some new shit in a few days, or whenever. I'm not saying it's flawless, but the female experience on tinder is ridiculous. This chick showed me her roster and it was like triple digits deep. Do what it takes to stand out, fortune favors the bold. Try to make em laugh, say some crazy shit, and be yourself. You've got nothing to lose.
Until you're holding in your farts over a couple beers and telling some shitty jokes, all you're doing is looking at a face on a screen.