Not government, not Elon Musk, not Blackrock, etc are the Bitcoin competitors.
The biggest Bitcoin competitor is centralized exchange, they're creating a fake system that harm the decentralization. Unfortunately most people don't aware with this and they still use CEX to exchange or hold their coins.
what stops them from building a coin on the block chain that'll bypass the total sum of bitcoin users, and regulate it?
There are already more than 20K altcoins exist until now, is there any coin ever overtake Bitcoin? nope, it's proving anyone who create a new coin can't beat Bitcoin.