[rkido]

This is a question of margins, so you're neither right nor wrong.

It normally isn't just 0.1% of sales when developers do get everything right, although whether or not the usual 1-5% of sales is worth it depends on the particular game, budget, and sales numbers. Linux support clearly wasn't worth it for Planetary Annihilation due to its low sales numbers, but a game with (1) high sales and (2) easy porting process would be leaving money on the table not to support Linux.