I might expand the commentary by mentioning some things about top-level bridge. First of all, most teams (of 4, more likely 6 to allow a rotation/rest) have a sponsor. The best pairs certainly get $1000/hr or more at a top event. But the sponsor also plays, and indeed I think you have to play 1/4 of the hands to have the result recognised. Now most sponsors are not that great. Nickell's success is partly due to the fact that he is a very strong sponsor. Maybe an Elo of around 2550, while many sponsors would be 2200-2300, some of the better ones 2400-2450.
Nickell also hired the best pairs, notably Meckstroth/Rodwell. At their peak, I don't think 2850 is an overestimate for them together, certainly 2800+ typically. Solovay, Hamman, Wolff, all at least 2750, maybe 2800. Nickell's partner, Dick Freeman, maybe around 2650, but he also had the right temperament with Nickell. So the team average could easily be 2750.
Now compare this to the likely #2 team at an event. Probably the hires are 2750, 2700, 2650, 2625, 2600, and the sponsor 2400, for an effective Elo closer to 2625. Maybe a couple of other teams exceed 2600, so a typical 150 Elo edge in the final is not out of question (assuming Nickell qualifies). Of course, it varies from event to event, but this is an average.
Why don't the others "band together", say 4 of the top 10 (either in the US, or importing foreigners) play all on one team? One reason is politics, many players don't like each other. Another is pride, being the top player (or pair) on a team is an ego thing (and maybe pays more). Funding 2 top pairs to fill out a team is another issue. On the international level, most countries would be lucky to have four players at 2650+, and due to fatigue, 6 players are almost necessary (not every country has a sponsor on their national team like the US teams tend to do, it depends on the selection process).
So that gives some idea why Nickell was able to "dominate" (that is, win over 1/3 of the major events) over a 15+ year period.