Here we see a practical warning about the persuit of philosophy.
If you desire philosphy, prepare yourself from the beginning to be ridiculed, to expect that many will sneer at you, and say, "He has all at once returned to us as a philosopher; and whence does he get this supercilious look for us?".
This is pretty straight forward: when you try and better yourself, there's a good chance that people will assume that you now think you are better than they are. They will try and bring you back to "normal".
Do you not show a supercilious look; but hold on to the things which seem to you best as one appointed by God to this station.
But, don't think yourself better than others, and stay true to your philosophy.
And remember that if you abide in the same principles, these men who first ridiculed will afterwards admire you; but if you shall have been overpowered by them, you will bring on yourself double ridicule.
At first I thought this was an appeal to common pride, but I think it's more than that. It's a warning. By quitting part way, you simultaneously show your inability to remove the influence of externals over your life, and give those externals a whole lot more ammunition. If you don't think you can weather the derision of your peers, you would be better off not pursuing philosphy at all.