There is a difference. And let me tell you a secret…there may be a few readers out there who enjoy watching the protagonist make stupid decisions and have to face the consequences, but most of us do not. It will drive your smart readers crazy!
Now, this doesn’t mean your protagonist has to make good decisions all the time. In fact, they can make stupid decisions on things that don’t matter (like naively getting cheated out of their money by a used car salesman). Sometimes those things make the character endearing. But if they make stupid decisions at plot critical moments, I am likely to start rooting for the antagonist.
Now, I will say there is a difference between a stupid decision and a bad one. Even well-intentioned people make bad decisions all the time. This is because we try and decide off of the information we know and we never know everything (also because we have blindspots and biases). All of this is very good plot material.
But stupid decisions are when characters suspend their reason or go against their character. They force you to follow them down a painfully stupid path.
When a good character makes a bad decision you can still feel sympathy for the character. You may also find it relating to tough situations in your own life and so you root even more for the character to come out on top, learn wisdom, and still fight for what’s right. I have to say I don’t know if I’ll ever be tired of watching complex characters navigate bad decisions.
But I’ve seen enough of stupid decisions in real life. I don’t want to relive those onscreen or on-page. Just saying.
Some writing advisors out there will have you believe you need to take every situation to the extreme, milk the drama, and play with the reader’s emotions until they have a heart attack. Don’t do this (unless this is specifically part of your genre and you know your readers love it). Otherwise, aim for balance in all things. Yes, people pay money to go on roller coasters, but then they go back to their lives. If you want to write a piece that will impact their daily lives and even integrate into their thoughts then you have to achieve balance. (And by the way no everybody likes roller coasters).
If you make a mess you are going to have to clean it up- so make a believable mess that the reader is willing to help clean up.