Philosophers don't "vacate the field". Many, maybe even most ethics texts are directly applicable to one's life. It comes with the territory of a field based around asking "What ought one do?".

They do tend to enjoy less market success than the less rigorous slop, but that's a symptom of a much broader problem in the world: Someone dedicated to doing something well is at a disadvantage versus someone dedicated to winning. It's the whole "anyone who is capable of getting themselves made President should on no account be allowed to do the job" Douglas Adams quote, it's why it's still not the year of Linux desktop despite having offered the superior OS for years, it's why IKEA has practically killed the market for quality furniture, and it's why damn near every corporation you can name is lead by some ghoulish psychopath. In most competitions, you can simply get a lot more mileage out of optimizing for the competition than you can squeeze out of the underlying skill. So the dude optimizing for selling books is going to knock the socks off the one trying to rigorously convey a robust ethical framework.

If you can fix that basic flaw in society, I think we should probably start with the more pressing matters than who's selling more self-help books.