I think the point is that if you do have a business or starting one, then don't take your eye off of that because you're feeling like you're not social enough or that you're missing out on things.
You can only do one thing at one time, right? So if starting/running a business is really truly important to you, then run that buisness. It doesn't make sense to start a business, raise money, hire others if what you really want to do is go to a club and hang out 'till 3 in the morning. It does have to be one or the other, or that business will fail.
Now, I'm not saying not to do the social stuff. Friends and relationships are very important. What I believe Larry is saying is to not take your eyes off the prize. You've started the business for a reason. You need to be focused on it and nurture it until it succeeds. If you really don't want to put in the time for that, there are other alternative like getting a regular job. Then you can work 8 hours a day, have friends, and party. That's fine.
To be successful as an entrepreneur, you've got to dig down deep and take care of your product. Its a lot of work. A ton of work. If it wasn't, everyone would be doing it. Instead, we have a few people trying to start/run businesses. And it can be Hell. But, if you don't want to deal with that extreme focus, that's fine too.
Think of the movie Cool Runnings. While the other Jamaicans were at the Ho Down Bar, Derice was sitting in the tub going over turns. Its that type of focus that will help in succeeding at business.