Sure. Why not? There are lots of companies in the world that sell proprietary software. Nothing wrong with that. A lot of great software in the world, from a user experience perspective, is proprietary. Think about the devices, computers, and websites that you use on a daily basis - most of these are probably proprietary. I don't think there's any moral obligation for someone to give their work away for free as open source.

Let's just not confuse proprietary software with open source software.