Yeah, the lab time at th10 is stupid. This is why anyone with a max 9 is just selling or keeping it at 9 forever and buying a 10. This is the central issue the game has right now. The more content they add the more they add to the insane time to actually carry someone thru it. It's a feedback loop that will prevent new people from coming into the fold.
And if you are done farming there's not a real incentive to stay active farming. You can build an army and practice in FC for a bit, attack in war, go away. This was a huge issue in onehive genesis where I was for a bit. The th9s are all basically done. There's no reason for them to do anything but show up for the first 6 hours of a war, collect their two 3 star raids and check back for the last hour of the war to see if it was won. None of them have any interest at all in moving their accounts up. They realize how stupid a 9 to 10 move is right now. That has to change, but I feel like it won't.
And not everyone wants to go thru the hassle of buying accounts either, I mean it's not like you paypal someone some cash and boom. There's alot to it. I don't want to make it seem that simple, but trading with a known person it is quite easy. Especially on android.