Should a seed investor for a startup be given the right of first refusal to purchase 100% of all money raised in the future?

It’s definitely not a standard request.

It puts you in a really limited situation offering 100% of revenue to the investor and you really have to think long-term when it comes to business. I would encourage you to listen to the advice of your attorney and also make sure that you got through all of your agreements with this investor (if you choose to keep him around!) with a fine tooth comb. As others have indicated, there are other investment options out there and you may very well want to consider diversifying your investors and looking elsewhere. Again, not a typical set up.