Money on mobiles?
Most mobile developers make no money. Not real money you can live on in the US or Europe.
So making one really "deep" game and releasing it on steam could make you more money than all the mobile games you release from today to 2030. Of course there are no guarantees either way. Most games on Steam make no money either, but that is because they are garbage mobile like games or re-skinned Unity tutorials/assets. Real games on Steam do seem to still make at least some money.
Sure, you may get lucky and your games become as hit, but odds are about the same as winning a lottery.
If you have a day job and do not depend on this one game you want to make, I'd say go for PC since that is what you prefer and like. Even if it flops you still have a job and a game you made your way. With mobile games if they flop ( most likely scenario ) you will have a bunch of flops and shitty games even you do not like.
And finally, there is nothing preventing you from working on one big PC game while simultaneously working on a couple of mobile games ( let's say a couple of hours every few days for that, when you don't feel like working on anything else and are stuck with big game development and need a break )