Well if only we knew that even a small amount of trading on uniswap will give us free uni airdrop we already do that. But no one knows that uni will give airdrop to its users. Lucky to those who made thousands because of uni airdrop.
It's the risk and reward system that we'll never know if a project will become successful. Lucky people who have trusted or just tried to make sure if the project is good as Uniswap as an exchange and its base user have increased dramatically.
Even before the airdrop, they've seen that the project is growing and they've just rewarded those people who used them before the given snapshot or deadline.