Here are some revelations. Firstly, chess is a sport. It's not called that by formality, it actually is a sport. It takes both physical and mental endurance to play the sport at a high level. This seems silly to anyone who has never seriously played a 6-hour game, but it does not to anyone who has been through that experience. Especially if you start dozing off at move 50 and make a blunder that pours half a day of work down the drain. Then you realize going to tournaments and doing this frequently at a much higher level must put a big strain on both body and mind.
Your mental faculties and your body both deteriorate, starting when you are around 22 years old. Experience may seem very useful in chess, but opening theory is constantly developing while the rest of the game relies on pattern recognition and calculation. These skills do not improve beyond a certain point which a player like Anand has reached decades ago. Thus, experience plays a limited role in chess and does not properly compensate for the deterioration of your mind and body. At a certain point you need to put in many hours of practice every week just to keep your skills from deteriorating, all the while your body is deteriorating regardless. In a game like chess, this is not as noticeable as in the more physical sports of course, but it is nonetheless significant and thus it is exceptional that Anand has remained in the top 10 for such a tremendously long amount of time. This is the exception, not the rule.
So instead of wondering why Anand is falling off, I would wonder why he has been able to maintain such a superb position for such an incredible amount of time. It's the exact opposite of the proposed question, which indeed comes off as a bit ignorant as people have pointed out, considering that Anand is not just "still good" but rather "still among the world elite which has been developing and growing constantly while he was getting older". It's amazing, really.
The rest of the question is a bit unclear. I have no idea how I could possibly know something about an elite player that cannot be found on the internet and I don't know what kind of specialty you expect surrounds players who sit behind a board and make good moves very consistently. Aside from the few rather strange fellows like Fischer and, to a lesser extent, Kasparov, most chess players are just people like you and me.