It was necessary to buy altcoins in December, when they were at the absolute bottom, and not now when they grew by 200-500%. If you have a small deposit, then you can transfer part of the funds to promising altcoins (better, absolutely new projects with the support of top funds, and which have a small capitalization). In this way, you diversify your portfolio, but you should not sell bitcoin completely, since altcoins are not always stable and often not only grow rapidly, but also quickly fall in price.