Even if I had a 'legit' startup, I would not let my parents or grandparents invest their life savings into it. Startups are not for retail investor's retirement funds.
There's the difference between investing in the startup (taking shares in a specific company) and investing in crypto though, right? I'd happily encourage my parents or grandparents to invest in an 'index fund' of startups in a bunch of different fields. I can't say the same about an index of crypto companies, and especially not in an index of crypto assets.
AFAIK, there is no such thing as an 'index fund' of startups.
But even if there was, purchasing a L1 coin is similar to investing in a wide swath of coins, because if the value of startups build on the coin increase in value, then there will be higher demand of that coin.