While it is true as you imply that Venture Capitalist (VC) tend to sell their tokens below the presale price, this is not always the case. They may have a variety of reasons to sell their tokens, including diversifying their portfolio or taking profits. Additionally, some VC may have lock-up periods or other restrictions that prevent them from selling tokens immediately after launch. Normally the price at the time the token is launched, factors like market demand, utility, and overall market sentiment play an important role I think.
VCs are coming in for the profit not for the welfare of the rest of the investors. They do have lock in periods and these are never declared to public investors but only inside closed door meeting with the VCs. Once that lock in period ends, they dump immediately and cash out of the project. That is the major time when the project loses ground and the investors are left with nothing but dust because the projects rarely come out of that dump.
This has been the reality with many projects if you look through the history. One of the reasons why you should give a project a couple of years before investing and if invested early, exit early too.