One of the most diversified equity funds you can buy is the Vanguard ... it pays to use certain index ETFs to focus your investment. You don't need to have years of experience to invest in stocks.
All of this leads ultimately leads you to the biggest challenge of starting a private equity fund, which is convincing others to invest in your fund. Firstly, prepare to invest your own fund.
You may lose your entire investment ... Yes, normal people can invest in startups. To invest in individual startups, equity crowdfunding portals like StartEngine and Wefunder are best.