Should scientists spend time, money, and resources so that people can live 100 years or longer

Yes. In the end this will pay off as we will live for longer and be able to accomplish more.

It is all a matter of opinion. In my opinion, no they should not for a few reasons. Firstly, it would result in overpopulation because there would likely be twice the amount of people that there are now. Also, if scientists are able to extend life for 100 years, people will most likely want to extend it for another 100.

Hope this helps