Look for companies like Basecamp, companies that arent looking to be aquired or get unicorn status but to stay soundly profitable year-after-year.
This was one of the reasons I loved WhatsApp so much early on when that seemed to be the way it was going: a healthy >1B USD company with no dependency except on users.
As the WhatsApp story and many other tells us this isn't always safe, but it should be a safer bet than anyone clearly going the "unicorn or nothing" way from the start.
Was WhatsApp healthy or profitable before it was bought by Facebook? I'm not sure if there's any way we can know for sure, but it all played out like a pretty standard Silicon Valley "unicorn" - couple of rounds of investment by a big VC followed by a mega-acquisition by a FAANG.
Do we even know they are profitable now without Facebook selling user data?
But WhatsApp is an insane success story on its own. Back then, around 20 engineers handling billions of messages per day, with their own servers and spending zero dollars in advertisement and using a non-standard language (Erlang).
They had 400 million monthly active users in December 2013. At the same time they had 50 employees I think as well as modest server expenses.
They had signalled quite early that they where going to charge money, they had started charging money from at least a subset of users and they were still growing like crazy, 200 million monthly active users since april that year it seems based on the statistics I found.
At least with a startup you can count on them to, well, try.