There's nothing wrong with selling software.
But there's something really wrong with selling COPIES of software, when the amount of money to make a copy after a master exists is negligible (even more so now with digital distribution).
Free software can be supported by donations, for example. But someone needs to come up with a better way of selling software without resorting to selling individual COPIES.
But it doesn't seem like you're factoring in the amount of money that went in to developing and writing that software. Sure, a COPY might not cost much, but the initial program, the master, probably cost a fortune. They make that money back selling copies.
Free software and donations may work for some companies and some software, but not all. It's naive to think that all software should be free.
I work in video and I hear this argument all the time. "Why does it cost a lot to produce a video? A DVD costs less than a dollar." Well gee wiz. Maybe because you aren't being charged for the DVD, but the content that is on it.