It doesn’t really work that way because all home ISPs sharply limit both your upload and download capabilities. If you try to serve millions of customers it would pretty much break the Internet for your neighborhood and everyone else on the trunk even if your ISP didn’t throttle.
Your local internet goes down -> service goes down.
Etc. there is a reason cloud computing is valuable. If you aren’t able to keep your service online enough or to an SLA then customers will look elsewhere.
