It is thanks to the enormous intellect of Rick Sanchez that he is able to go on so many weird and wonderful adventures with his grandson. While there is a wide universe out there to be explored, with literally countless stories waiting to be told, none of them would be possible without Rick.
He invented the space ship that carries him across the universe, he invented his portal gun that allows interdimensional travel in mere seconds, and just about every story in some way or another comes back to him being the smartest man alive.
However, that doesn't mean that he is completely impervious to the odd brain fart every now and then. Even the smartest man in the universe can be so dumb that it is almost unbelievable. He can look down on the rest of the planet's population, particularly Jerry, all he wants, but sometimes he is no smarter than the rest of us.
Whether it is overconfidence in his own abilities, experiments that never should have even been thought about, or just Rick's sheer laziness and lack of commitment to what he is doing, there have been times when he has even made Morty look intelligent by comparison.
9. He Let His Guard Down At Birdperson's Wedding
Rick's relationship with Beth's mom, and the circumstances surrounding her disappearance and his return have been shrouded in mystery since the beginning of the series. There are fan theories galore surrounding the subject, but all that can be said for certain is that Rick came out the other side with a certain disdain for marriage.
He showed as much when he and the Smith family were invited to Birdperson and Tammy's melding ceremony on Planet Squanch. However, he was too focused on his journey from believing he was losing his best friend to opening himself up to the idea to stop and actually think.
Birdperson and Rick made themselves many enemies over their years as friends, and found themselves labelled terrorists by the Galactic Government. They were living their lives in hiding, yet when Birdperson invited 17 of the Federation's most wanted to the same place, bringing them all together and out into the open, Rick didn't even think about the danger that put them in.
Rick can hardly be blamed for not knowing Tammy was a deep cover operative, but he should have had his guard up while on a strange planet surrounded by all of his terrorist friends.