This is not how investing works, it's that simple.
If you want bigger returns you will have to accept higher risks.
A single starting company is never an alternative investment compared to a much larger spread across a series of established companies.
Investors work with risk by having certain portions of their available capital earmarked for investments in particular risk segments. Typically a large chunk will be allocated in 'safe' (for want of a better word) investments, which may indeed be index funds, real estate or other such. Another portion may be invested in more risky but higher yield such as larger investments in a single blue chip stock that the investors feel good about. And finally there is the bucket 'gambles'. These are considered very high risk and are either huge wins or huge losses, rarely mid range returns, in fact (for the investors, not the founders) they'd rather the company gambles big than to end up playing it safe.
But if such a company is in a spot where it will likely lose it all and then a plan to end up returning the investors just their outlay is already a huge plus, and if they manage to make the investors look good by posting a return, however slim then that will be a much larger win: investors, especially those with LPs do not like to post write-offs not because of their own book (they pocket their management fees regardless) but because it will impact their ability to raise again.
I should probably write a blog post on this one of these days.