So these people make very little money on their business yet think someday they'll be able to sell this business for a lot of money? Sounds like they might need a reality check; who's going to buy an unprofitable business anyways?
This isn't short term thinking. It's the opposite.
Allowing the super wealthy, whom are the actual ones that benefit from capital gains, accumulate untold wealth is clearly resulting it a multitude of societal ills (including the dismantling of democracy itself here in the US).
Looking at even a little bit of recent history will clearly show you what happens when we let the super wealthy just get more wealthy (have a look at the Gilded Age).
The propaganda around taxation causing economic slowdown is so tired...