Artists pass the flame after 30 years old

There are many art community (like Deviant Art or GF Artist) which help artists to sell artworks on-line. And if you pay attention to age group of such artists, the basic share - people from 20 till 30 years which have started to paint since 14 years old. On portals where sell reproductions of art prints and posters, hardly you will see these artists. Practically all portals which are guided by the modern art, sell artworks of 40-50 years artists.
It means that time for reception of popularity after 30 years is necessary for "newbie" artists. Art as wine, than longer endurance that it is more tasty.