Investing in a bounty, whether it's following an airdrop or buying when crowdsale, is certainly 100% pure speculation, meaning that no one will guarantee that after that the project will be successful even if it is managed by a good dev and has a good community.
I have participated in several bounties and bought their tokens when crowd sales, many of which failed and cannot be listed in the top market, so they do not have good sales value, and some of them have also been included in the listing, but the prices are get not in line with expectations.