Stan and Stan, whichever you subscribe to which name until canon proves otherwise, have their separate strengths and weaknesses. Sure, The Author probably went to college, majored in the sciences, and had talent in the arts (probably went to an arts and science school, haha), but that doesn’t technically make him the “smarter” twin. Like Dipper and Mabel, their genius lies in different fields.
For one thing, Stan is mechanically inclined. He created his own vacuum cleaner from scratch, as shown on the billboard in NWHS. They weren’t wildly successful (I think the billboard said like, 99% malfunction rate? haha), but it was his first real invention and a proof that he knew how to tinker around. Not only that, but it’s possible the Stan Vac was also his first major con; selling vacuums to people at a cheap price and then skimping out when reports of malfunctions came in. It’s not hard to simply drop everything and stop selling when you’re traveling and hard to get a hold of. He may have made quite a quick buck off of those old pieces of junk. Interesting to note though that he still HAS Stan Vacs around the house; there’s one in his room and one in the hallway closet. He must have a soft spot for that old junky hardware.
Let’s also not forget that Stan did upkeep on his car for 50 odd years. He may have completely rebuilt the portal in 30 years all on his own. He also re-purposed the house into the Mystery Shack and is a slippery devil that can escape almost any sort of imprisonment situation. He fooled the world for years; possibly his whole life. We only really know a fraction of the things he got up to, while his “goody” brother went off to college and got himself a right education. But it’s clear that while both twins harbor inventive genius, both of them also hold MANY secrets, and probably a lot of laws broken in the process. It’s probably gonna blow all our minds when the next episode comes out and reveals some more of those hidden secrets.
I personally cannot wait! But I agree; Stan needs some serious credit. He’s an amazing guy with amazing talent. he’s had to keep up a facade for a great portion of his life. It will be interesting to see his character develop with the arrival of his long lost bro-bro.