Simple question: as i see, it has lots of advantages, including the one that makes everybody pay attention: price (huge). Why then it has not gone mainstream yet?
Thank you in advance for ur time and answer.
The network was released just 2 years ago, and a project like this don't become mainstream so fast in the same way Bitcoin will still require several years to become a mainstream currency.
The most honest reason is that the product is not totally complete. It works, and renters can upload (and everyday upload) their files and backups, but there is still much work to keep doing: beyond 5 Terabytes uploaded the client starts to freeze, there are certain bugs some renters experience, native file sharing and file streaming is not yet allowed. Fortunately, solutions to all these points are in their roadmap, and for instance next release on September/October should revamp the renter experience and increase the cap to 40Tb.
Also the independent developers have to keep creating tools and services over the Sia network (like storage services that accept FIAT and do the Sia thing behind the scenes), and keep creating integrations with popular services and tools. The dev team created last month a campaign of bounties to encourage independent devs to achieve these integrations. Last month it was Minio (a popular storage server container compatible with Amazon S3 or Azure), last week it was Duplicati (a popular backup service) and more bounties will come.
Bottom line: While it is a working product, there is work yet to do. But step by step Sia is getting there.