If a project offers 20-30% of the total supply for bounty, it's really a bullshit and scam project. Only 1-2% for bounty has caused the project to collapse, and if they set a higher budget then their project will surely fail and no one will invest and buy them.
Its rare to see a project offering this big. Maybe none in my entire life of doing bounty. Not sure about the higher the budget it will collapse the market. There is a thing called improvised, even the rewards are big they can do a montly distribution and divide those reward fairly so it would not absurdly drop the market. I seen this being done on some project and it actually helps. The latest one is cartesi project which divided into three parts even though their budget is not that big but good strategy to avoid massive dump.