Oh wow, that's simply not true. Many investors have spent more than that to prove a point. Sometimes in one place, sometimes over many places and years.
Who has invested $1B+ in something they expected would lose money just to "prove a point"? And what was the point?
And Musk buying Twitter doesn't count because he was forced to buy it after it became clear he would lose money. He did everything he could to get out of it.
People don't generally spend $1B to prove a point.
They'll spend it on a network of users that is genuinely that valuable though. That's what Zuck did in dropping $1B on Insta.
And it seems entirely possible that if Insta were built today, it could be done with a single person.