You don't need to interpret what Musk might mean. Musk publicly predicted people on Mars by 2025, then 2026, then 2029. He predicted a million people living on Mars by 2050. He has been specific, if not consistent.
I don't see how humanity will go backward if we don't colonize Mars. That's the kind of thing a cult leader says.
In the meantime Musk is squandering $44bn to buy Twitter just to show that he can.