Is venture capital profitable besides for the top tier VC firms?

Yes — but there are two types of profitable.

The very best funds try to return 5x the capital given to them, and occasionally, even do 10x.  (Very small funds can do better, but let’s put that aside).

Rough-and-tough, a fund that can return 2x net probably can return about 15% IRR.

So a 2x fund, net of fees, is OK but not great as compared to Nasdaq.  A 3x fund, net of fees, is pretty darn good.

90-95% of funds don’t do 3x.

But …

that doesn’t mean the fund can’t be “profitable”.  The partners can make a lot off management fees even in a 1x or worse fund.  And an even a 1.5x-2x fund can be very lucrative for the partners, even if it’s mediocre for the LPs.  The IRR could be quite low, but if the fees are high and the partners still get to keep 20% of the gains, the total compensation can be substantial.