For one individual to make their own decision to do those things, no issue.

But when a group of wealthy elite make it their mission goal to vacuum up money from everyone below, that's disgusting. The executive team at GS decided that they wanted to hire programmers to handle investing, instead of hiring programmers to handle nobler tasks.

At least when Google develops banner ads, they are providing value to the millions of people who need to advertise. When GS develops a better trading algorithm, you can count the number of people on one hand who benefit.