In theory you absolutely could, but be prepared to encounter many challenges that you will need time, money, and infrastructure to address - and for this reason, we do not recommend it unless you are truly determined.
First of all, most ISPs have clauses that do not let you use your internet connection for web hosting - doing so will result in termination of your account. Already, you will need to consider a more expensive and complicated internet service agreement & infrastructure with your ISP before even thinking about reselling your connection. By default, most ISPs block connecting to the ports required to run a website (namely, port 80).
Secondly, consider security. This includes ensuring that your system is secure from hacking on an on-going basis, keeping your computer online 24/7, upholding service agreements with any and all users, and more.
Thirdly, the issue of performance. Most good web hosts use powerful servers with abundant RAM and high-performance solid state drives. Furthermore, they have multiple internet connections at speeds far higher than what residential DSL or cable service can provide.
Lastly, there are all the issues of support. If something goes wrong, it will be your job to fix it - you will not have a professional to correct the problem.
If you are not deterred by any of the above, then we wish you success in your future hosting endeavors!