I think it really depends upon the severity of it. Those that actually go in to get a diagnosis are at least moderate on that spectrum or possibly even severe. However, there are tons of people that probably would be on the spectrum that are mild/high functioning that otherwise aren't aware, as there never was a need to seek out a professional.
We've discussed this before, but I'd wager that a very large/majority percentage of men in fields like engineering, physics, mathematics, etc. would be on the spectrum.
For those that are high functioning, I think you'd find that maybe they had a hard time with socialization when they were growing up and were perceived as awkward but still capable of making friends. Dating would be also be a challenge but I think they'd eventually be able to figure out what works and what does NOT work. I think the problem is if you take someone like this and they are in a set of circumstances where their socialization is limited and they don't develop these skills.
For those that are farther on the spectrum, I think it may be incredibly challenging and to a point where it may be impossible to overcome. Also, I've noticed that those in this category tend to have other issues as well.
Now, that I'm getting older I think I am/was on the spectrum but very high functioning and not all that bad to be honest. I have a hard time connecting with women on an emotional level but I'm able to easily have conversations with most men, especially intelligent conversations, debates, etc. I seem to have a very difficult time interacting with both women and dumb and overly emotional people. The reason why I think I may be mildly on the spectrum is because I have a tendency to get hyper focused on certain things in my life and can robotically stick with life routines. I also have a low need for socialization and in certain social settings I feel drained afterwards, though this may be more due to overall introversion.