There are quite a few instances of single asset vaults offering great APY, such as Cake, Stella, BIFI, however, you should always take into account impermanent loss, market crashes, such as the one we're experiencing now, BIFI has lost over $300 in value in the past week. You'll need to be extremely patient, especially in periods of depression, while choosing the correct project is a strenuous procedure.
I would assume that the best case in that situation is "everything going alright without a problem". When the situation is good enough that you would be doing fine unless some unexpected thing happens then there is no problem. I mean I would see Cake and BIFI and all that as a great investment because they should be making you a good amount of money and that shouldn't be going south anything more than the market to be fair.
I mean yes there are chances that it could be going down more than what it normally does and that is a problem but at the end of the day what is the chance of that? Like what’s going to happen, cake gets hacked? Doubt that.