Eventually the market will figure out that they don't need
to pay Steam 30% of sales to host files on a server
That's overly negative and pretty disingenuous. App developers for Android can sell their APKs directly and save 30%, but they don't because of the convenience of the market.
Similarly, I rarely buy games outside of Steam (or GOG) except in the cases of very indie developers who provide a steam key when I buy directly from them. The Steam service is a good one. When I build a new computer, I just need to install steam and my entire library is ready to install. Valve have rightfully found a gold mine from a service that they made that is a net value to consumers.
And even if Steam didn't exist, a non-publisher-specific store is still needed. I'd go to GOG (for similar reasons as I use Steam).
Yeah you're right, Steam does offer a lot more than just file hosting. They also do DRM, friends lists, games promotions, and modding marketplaces, although each of these things certainly also have cheaper/decentralized solutions.
The 30% number is one that they might start to get pressure on with competition. GOG now pulls something like 10% of steam sales on the games they curate (citation needed) and I believe they are working on a stronger community/online platform.
There are also more indie upstarts like http://itch.io, which are smaller but focus on developer outreach and close-knit community.
Similarly, I rarely buy games outside of Steam (or GOG) except in the cases of very indie developers who provide a steam key when I buy directly from them. The Steam service is a good one. When I build a new computer, I just need to install steam and my entire library is ready to install. Valve have rightfully found a gold mine from a service that they made that is a net value to consumers.
And even if Steam didn't exist, a non-publisher-specific store is still needed. I'd go to GOG (for similar reasons as I use Steam).