You clearly don't understand the meaning of budget.
Things like his computer, food, etc. are not accounted for in the games budget, because those expenses would have been there even if he didn't make this game. The game's budget is the amount of money allocated for the singular purpose of making the game itself. That 30$ is just the additional expense that added to default expenses on account of making the game. He developed this game in his free time. If you play a game in your free time, and consider your expense on said game, you'r looking at the cost of the game, not the cost of your continued existence.
If I purchase, say, GameMaker, which costs, say, 30$, and then make a game using said software, and nothing else (which is possible), then the budget of the game is 30$
. That is if I bought said software for the soul purpose of developing said game. The budget of something entails only, only
, the expenses that would not be unless the project would not have been undertook.
OT: It's guys like this that elevate indie titles over the consistent AAA excrement of brown-gray boring over-priced sludge.
Way to go'