Ivey was pretty good at managing his image, too.
Almost all pros who have had success both online and live agree that live games a ridiculously soft compared to online games. The reason more online pros don't play live is because you have to live in Las Vegas or Macau to play a the highest stakes, or you have to be invited. Also, the big live games are usually mixed games that don't afford a huge edge to online pros who specialise in a few games.
He is a top pro. Not in HU cash. He couldn't hang with these guys at HU cash, at least not with his current skill in the discipline. But hey, poker is not that narrow of a term. It includes all kinds of disciplines, live and online, horse and stud and hold 'em, the list goes on.
Those same "top pros" who Negreanu wouldn't play HU Cash wouldn't sit in the big game with him.
Arguably bankroll management is the most important skill of a top poker professional, and that's maybe what big-game players are best at.
Also, a small caveat to all of your comment is that live games are soft compared to online games of the same limit. There is no online equivalent of the big game, or at least there wasn't when black friday hit and knocked me out of the professional poker scene.
And while bankroll management is certainly an important and required skill to endure as a professional poker player at any level, it is by no means what differentiates high-stakes pros from pros at the lower levels. There are lots of small stakes and mid stakes players who practice sensible bankroll management, but who will never acquire the skill necessary to make it at the highest levels. If you want to get a sense of how much skill goes into playing poker at the highest level, you should watch some of Phil Galfond's strategy videos on YouTube (see for instance [1]). Poker strategy has come a long way since Super System[2] and The Theory of Poker[3]. Even players who were considered very good just five years ago, can no longer compete at the highest levels.
[1] https://www.youtube.com/watch?v=khdoSFCQ9iA [2] https://en.wikipedia.org/wiki/Super/System [3] http://www.twoplustwo.com/books/poker/theory-of-poker/
The Big Game and online HUNL are both technically "poker" but they are truly completely different games.
The post I responded to slighted Negreanu, saying he wasn't a "top pro." He certainly is. Not a HU cash pro, of course, but a top pro? Absolutely. A match for the "best pro players?" Certainly.
The "best pro players" in a given niche wouldn't have sat in the big game, and he wouldn't have sat in their specialty. Overall he's the better poker player.
Up to 2010, Negreanu had some up and down and as poker theory developed, his game showed a number of pretty big flaws--which he himself admitted. Sure, he was a competent player, so calling him just a 'celebrity' might be misleading, but there were many players in the top online scene who did a lot more of volume and analysis that Negreanu, who pushed more edge and who leaked much less.