The persona is *mostly* an act. He's an attention whore, yes, and his persona fulfills that need, but he admits some of it comes from being a sore loser and letting his emotions take over. He's usually very apologetic after he goes off on someone, and has said many times that he wants to curb that negative energy. But I think it's too much a part of him now and he's not been able to control it lately. Witness his near fetal position breakdown when he was sucked out on and eliminated in that WPT event.
Virtually everyone who knows Helmuth personally says that away from the table he's the best friend you could ever want, extremely loyal and will give the shirt off his back to anyone who needs help. You see Mikey giving him grief all the time on TV but the truth is they're best friends. In Mikey's book he speaks very highly of Helmuth as a person and a friend even while insulting his poker abilities.
His cash poker skills are as bad as his tournament skills have been good, but the game has changed a lot since his heyday and although he can still be a force I don't forsee any more bracelets in his future. I have no doubt that players like Ivey and Sidell will break his bracelet record in the next few years. But unlike most other pros (with the exception of the FT founding pros Lederer/Ivey/Ferguson/et al), Helmuth is a marketing juggernaut who clears way more money away from the poker table than any other pro. His endorsements, appearance fees, and investments/business ventures earn him far more than even the biggest poker winnings, so you have to give the guy some credit for being smart. The vast majority of pros can only dream of the success Helmuth has had.