Dedicated DOTA player. I have a copy of beta and would be overjoyed to preorder the deluxe edition and contribute financially to the game. However I, like many of my friends, am a Mac user. If Mac support is not made available Riot Games will be losing out on a significant amount of sales. Recent sales data indicates that 94% of portable computers sold in the US last quarter that cost over $1000 were Macs.
This means that the individuals who are most likely to spend money on the non-free features of the game will be unable to play it without installing Boot Camp.
For the majority of PC-humping forumites who probably don't know the first thing about Boot Camp, let alone a Mac beyond personal bias, may I add that the majority of Mac users do not use the program. I personally find it a tremendous joke to be expected to turn my Mac into a PC in order to play LoL, sacrificing a large chunk of memory and exposing my computer to all of the OS bugs and problems I stopped using PC to get away from.
Icefrog, Riot Games, forumites, please get on the bandwagon for Mac/Linux support. It's what Blizzard Entertainment does. It's what most major developers do, and (regardless of what the majority will say), these niche players are income just waiting to be harvested.
tl;dr, but that's my two cents.