I don't feel sorry for them at all. I just understand that they have one and only one tool for bargaining, and that is their ability to refuse to work.
You think they should be villified for striking because of the magnitude of their salaries, but they likely wouldn't be making millions without the major changes in the labor agreements - changes that likely wouldn't have occurred without the threat of strikes.
I have a feeling that there is some salary level at which you might feel the players were justified in striking. What is it? 250K? 100K? Whatever the number is, you should realize that it is arbitrary.
NFL players are elite in their field. Their income is comparable to elites in other endeavors - doctors, lawyers, actors, traders, investment bankers - but they have a much smaller window for earning such salaries when compared to those other professions and much less capacity for influencing the rate at which they are paid.
The players and the owners have what amounts to a partnership, and the issue at hand is the fair division of the profits among the partners, not whether a person earning a seven-digit salary should have the right to ask for more money. Sure, the players might not be able to make the same salary outside of football, but the owners stand to lose a very profitable business if they let it get watered down by using less-than-elite players. Both sides have incentive to negotiate.
Larry Page and Sergey Brin founded Google as equal partners. Would you think it fair if Page had the ability to unilaterally set the value of Brin's ownership at, say, $30 million when the market cap of the company is over $100 billion? You might not feel sorry for Brin, the multimillionaire, but you could hardly begrudge the guy for following channels to get his fair share.
I'm not suggesting you should feel sorry for the players, merely that you ought not begrudge them for using the only vehicle available to them to determine their fair share.