Matic is an extension of Ethereum. All the people that love ETH are using Matic because it solves some of the main problems. If you already have a userbase and just redirect them, it's easy to grow.
On the other hand, if you want to compete with ETH, it will generate tribalism. Only the ones fed up with current issues will join the new project. It's hard to take over. Just like BTC is still king with many better projects available.