Pretty simple: you use spaces because you're aware that there is more than one IDE/editor in this world and who knows what your code will get opened with tomorrow. This means you consider consequences beyond "but it works on my machine" so you're a better programmer. Ergo, higher salary.
On the other hand, I find 2-space-indented code unreadable; in fact, 4-space wide indentation is the only size I find to be readable. I know plenty of people for whom that isn't the case. Using tabs lets the reader set the indentation level.
¯\_(ツ)_/¯
Edit: All the anti-tab arguments I'm reading below boil down to alignment. Don't align folks; there's good reasons not to align regardless of your indent style.