I think that copyright should not expire during the creators life. I can profit from my business activities for the entirety of my life, so should an artist.
After death? Absolutely expire that copyright. In fact I think that perhaps a limit of 14 years after death so that a widow can make use of it but no more.
They can, by continuing to create new work
The key word to your "business activities" is ACTIVITIES.
Further You seem to be under the false impression that the purpose of copyright is so creators can make money. No that is not the purpose.
Copyright has the sole constitutional purpose in the US to promote useful sciences, no other purpose. Not so creators can make money, not so widows can make money.
The ability for those people to make some money off of their work is entice them to create in the first place. Placing a limit on the time they are earn from the work entices additional activity including
1. Them to create additional works every 14-28 years
2. Allows other people to make use of that work to create additional work after 14-28 years
As was eluded to in other comments most of the IP locked away today is based on work that was created by others, a majority of Disney for example was inspired or directly copied from Public domain Works
The idea behind a 14 year copyright is to inject the Public Domain with a rich set of IP creators can use to create more works. Which is the purpose of Copyright not profit
1) In order to determine whether a work is under copyright, one needs to know not only about the publication history of the work itself (which is typically printed on copies of the work or accompanying material), but also whether and when the author died. For works by obscure authors, this can involve significant cost.
2) Works published late in an author's life or by an author who dies young receive a shorter term, even though there's no reason to think that they're less valuable.
3) It theoretically creates an incentive to kill the author to shorten the term. Although I suppose that this is quite unlikely to actually happen, why build such a perverse (in both the economic and moral senses of the word) incentive into the system if we don't need to?
Furthermore, it's not at all clear that term lengths on the order of a lifetime create any productive incentive compared to shorter term lengths. For the vast majority of works, revenue rapidly decays to a trickle within a few years of publication (for fast-paced markets like video games, this can happen in a few months). So starting from a term that's already decades long, an extra decade or two on a new work has a vanishingly small net present value [1].
[1] https://www.law.cornell.edu/supct/html/01-618.ZD1.html ; See Part II—C