I'm a righty. But I can well believe that there are more lefties amongst the intelligentsia than the general population. I also believe that lefties tend to be, on the average, a little more intelligent (10%?) than the general population. I get this from direct observation and have no official studies to quote. I also note that those who are involved in science and/or technology at a professional level also tend to be musical to some degree.
I myself play drums from time to time which is good encouragement to simultaneous two-handed dexterity. Coincidence?
Not sure if this is directly related to intelligence per se. My guess is that lefties and dyslexic folks have to try harder from a young age in a society made for right handed folks and during school and by the time they reach university or college they have an established work habits and perseverance better than other folks.
You can also see that aspect to people with good memories that got it easy until they hit first year of university where hard work and understanding of the concepts is all of the sudden relevant.
Dyslexic also tend to have good 3D and spatial visualization. Skills that are good for machining, topology, electronics and several STEM fields.