TTWO is stable, but not growing and also not in a growth sector of the market (i.e. AAA console games). Companies like Mojang are less stable, but growing rapidly and in a section of the market which is also growing rapidly and is simultaneously much more profitable.
Take Two's catalog are considered known properties without much room for significant growth or profit. Minecraft is a less known property, which therefore still has the potential to fall on its face but also has the potential to grow and create even greater revenue and streams at significant profit margins.
As an investor, would you rather put your money in Cottonelle or Twitter? Toilet paper isn't going anywhere, but it's also a market that's maximized its audience and which isn't very profitable. Twitter is still growing and has a far greater potential for profit, but is also much more likely to fall on its face and collapse than the toilet paper industry is. Both have their upsides. The same basic logic applies to Take Two and Mojang; in that case, people value the upside and profitability of Mojang more than they value the stability of Take Two.