The players probably value grand slams higher than olympics, yes, but is that really how it should be? As an athlete, regardless of the sport, I'd value winning an event like that much more than an event that I can win 4 of every year. And no other competition really gathers so many people around the globe as the olympics, it really is the pinnacle in sports overall.
What you're essentially saying here is that the frequency of the tournament decides how well you value it. Do you value winning the WTF higher than a Grand Slam? Or the Davis Cup? Or the Challenger Tour Finals?
Someone mentioned that it's much harder winning a grand slam than the olympics, and I really can't see that? Where's the logic in that statement, honestly? You have 16 chances (GS) v 1 chance (OG) in 4 years, and yet you believe it's easier to win on that ONE CHANCE than the other 16? Retarded logic. Just ask Federer how hard it is. One bad day and you don't get another chance until 4 years later, in a whole career you might get 3 chances at best - that leaves very little room for error.
The logic is that the competition in the Olympics is simply not as good as in the Grand Slams. In Grand Slams you qualify based on ranking, in the Olympics based on your nationality. The 2012 Olympics had maybe the strongest Olympic field ever and yet players qualified ranked 108, 138, 158, 304, and 418 in an R64 draw. 2008 was even worse with players from Togo, the Bahamas and El Salvador qualifying aside from the four Chinese players that made the draw.
The second argument is the history. Historically, tennis has not been popular at the Olympics. Would you rather be in the winner's circle of Murray, Nadal, Massu, Kafelnikov, Agassi, Rosset, Mecir, and Edberg, or would you prefer joining the circle of Djokovic, Federer, Nadal, Safin, Agassi, Johansson, Kafelnikov, Korda, Sampras, Becker, Courier, Lendl? And that's just the AO, the slam with the least historical appeal.
The third argument is the attendance rates at the Olympics. Tennis simply has to compete with a lot of other sports that generate much more interest at the Olympics because of their tradition there - Rowing, Judo, Athletics, Field Hockey, etc. The result is half-empty stadiums and nobody likes those. Same happens with Football every time, which is why they should discontinue both Football and Tennis imo. (there's my unpopular opinion)