Yes, but not focusing on money is how you end up building a business that sells dollar bills for $0.90. A few "for fun" startups have blown up in the past (Instagram, Snapchat, YouTube), but the reason majority fail is lack of business plan for how to actually monetize what they are working on. I don't consider focus on sustainability for a business to be a bad thing, though if a VC handed me $10m to spend trying to buy users I won't say no.
I think you should read The Black Swan. FAANG type companies are rare events. Nobody can plan a Unicorn company. They just happens. Look at the list of dead products that Google/Facebook creates every year. Even managers at FAANG don't know what is going to work.
You can focus on creating sustainable small software business. I don't know if you have read "Start small, Stay small" by Rob Wallings. It talks about creating a sustainable small business on the side.
I haven't seen that particular book and will give it a read, but I have attempted about a dozen lifestyle SaaS businesses. All went best like I was selling peanuts at an allergy sufferers' convention. I am always looking for more opportunities for something like this, but nothing so far has had the right overlap of profitable/my area of expertise/not requiring a stupidly high upfront investment.