Bitcoin is outdated in multiple ways, and it's true that it's big because it's the original. Long story short: it was developed by an academic as a proof of concept with an academic mindset and not an engineering mindset and it shows...

However, the new, more efficient coins are so many (and there are dozens of new ones every day) that it became difficult to distinguish between legit projects and exit scams, especially now that scammy practices like premine and PoS became the standard.