Total market cap is irrelevant when deciding to buy some coins since it is not really the total capitalization of everyone holding the coin(since some bought at lower prices). It would be a good thing to look into when deciding to sell, since high total market cap means that there are many holders(those who can also sell) and that total market cap can turn into a dumping force later on(if coin does not have potential for growth).
Thank you for your advice! Considering the current situation, if I understand correctly, there are not so many holders, hence it's a good time to buy top coins. Am I right?