Why is bitcoin considered the main one and its price not crashing from the threat of these other more equipped coins? Is bitcoin still able to develop and evolve and become energy sustainable and compete with faster transaction times if it is decentralized? No one is able to improve it?
Bitcoin is considered the main one (using your words) because we can only have one true bitcoin but as for altcoins, we can have as many as we want and just for the record the good ones are yet to be developed. Bitcoin has stood the taste of time (currently 10years and counting) so it has earn the trust of the community but the altcoins you speak of haven't.
Bitcoin is the most used cryptocurrency globally, that's it's the cryptocurrency with the highest adoption globally and finally in related to investment capital flowing into the market while altcoins have to share their allocations bitcoin doesn't have a worthy competitor that's why it's currently the leading in market cap.