Because he ate himself out of his potential. When he fought Holyfield the first time, he was in the best shape of his life. You can easily see the difference on all suceeding matches.
Terrible discipline and massive weight fluctuations. Plus, in a short career he took a mammoth amount of punishment in some very hard fights.
Basically overeating like a glutton, sometimes ballooning up to 300lbs before fights, meaning many of his training camps became "Fat Camps". Dehydrating & starving himself to lose weight, plus taking heavy punishment in brutal fights such as Coetzer, Holy I, Holy II, Holy III, Hide... A quote from Bowe on a HBO Interview before fighting Golota... "Larry why do I need to train hard for bums." (It's on Youtube somewhere.) Also, here's a nice extract from an article about Bowe training for Golota I: "...Meanwhile, Riddick Bowe has just won a rubbermatch against Evander Holyfield by eighth round knockout. Bowe is the top heavyweight in the world, loving the lifestyle, the fame and all that comes with it. This content is protected " Source
No dedication, no discipline. A dumb, stupid moron. No place at the top for a lazy bum. Now he's selling autographs on garage sale events. Sad story but that's how life is for those who don't work hard.
You dont get to the top of the world without working extremely hard, he was undisputed champ at only 25 He just lacked the dedication to stay at the top after getting there, he didnt lead the life & his conditioning affected his punch resistance
A combination of poor self discipline and style that saw him take huge amounts of punishment over a relatively short period of time resulted in his surprisingly fast decline. By the time he fought Golota he was already past prime at only 27 years of age. He was not yet completely shot but was far removed from the fighter who first beat Holyfield. During the second Golota fight he once again took huge amounts of punishment, that fight ended his career at an age where most fighter are in their primes.