I do believe we do must do both, because at crypto world, having some coin might mean we will get a bigger value, with saving, with investment we can grow our bitcoins fast as well risk to loose them.
We require to do both at the same time,investement cannot be done if you havent saved before so both should be done and we must realise when is the time for investement and how much we should should keep in our savings account.
Absolutely, one of them cannot be done without the other, because if you want to do an investment you will need funds which you will have to save at first, and if you want to have savings then you must have some investments running or generating some extra profits out of your income so that you get enough to save as well.