Well, the most important thing is develop good use cases. High APY is a good marketing. For projects on decentralized exchanges, it is one good way to attract people to provide liquidity and enable easy trading of the token. so, High APY is inevitable for projects on Dexes, except if the team is bouyant enough to provide enough liquidty. Even at that, one entity providing liquidity is a huge turn off for any project.

It is human to try and make profit, so people will always dump a whole or part of their farming earnings. But if the project offer good utility, it will continue to grow after the dump and after the APY is lowered.