Forgotten Artists

[Artdealer]

I noticed that there is a decent amount of forgotten artists, and from different periods. And among the impressionists, and among the avant-garde artists, and among the classics. I became so interested in the reasons for this: they are exhibited along with those artists who are a lot of millions, had their own exhibitions, and sometimes were even more popular than those who "survived" up to the present time. And what happened? Their names can be found only in art history books, and even then not always. Who has any opinions?