No, a lot of very good fighters go to Japan, equally good money and prestige in a country knowledgable and respectful of martial arts. Japanese comps are the Michelin starred places of MMA, the UFC is the McDonalds, makes a lot money, well known and is popular but not the best.
Japanese MMA is dying at a rapid rate. PRIDE died in '07. Sengoku is dead. DREAM is suffering from so much trouble that many fighters are complaining that they haven't been paid for fights that took place a year ago. (Gary Goodrich and Sakuraba to name just two.)
Look at Shinya Aoki. He's been dominating the Japanese lightweight scene for years, and as soon as he came to the US, he got brutally destroyed by Gilbert Melendez. Now he's stuck back in Japan fighting sub-par competition like Rich Clementi and Rob McCullough because all the best guys are in the UFC.
Or take the case of Jorge Santiago. He was the last Sengoku MW champ. He got picked up by the UFC after Sengoku folded and he's had two fights so far . . . both losses to guys who aren't even in the title picture.
The list goes on. . . Sandro, Omigawa, Takaya, Zaromskis, Hioki, Yamamoto. . . All guys who were top fighters (most of them title holders) who have struggled BADLY in the US.
You seem to have a bias against the UFC, which is certainly your right. But to say that either the best money or the best talent is in Japan (or anywhere else for that matter) is simply not an objective fact. The UFC pays well, they pay reliably, and they also have far more top ranked fighters in any division than any other organization in the world.