McLaren pipped rival Racing Point to third at the season finale in Abu Dhabi last weekend, with Lando Norris and Carlos Sainz finishing fifth and sixth.
The jump from fourth to third represents a significant step in the team’s share of the F1 prize fund, and may also have triggered sponsor bonuses, as contracts often specify extra payments based on championship performance.
The result came on the same day that McLaren announced significant new investment from a US consortium. However, Brown insisted it wasn’t about the finances.
“It's sporting prestige,” Brown told Motorsport.com. “The money's obviously nice. But when you're on the pit wall, you're thinking about it purely from the sporting standpoint. And then you get to the office on Monday, and you think about the financial side.
“The team's done an unbelievable job to do everything we've been through this year, bringing on a new investor at the weekend, and then clinching third in the championship when we had a very good car, but clearly last year's Mercedes is faster!
“Couldn't have wrote it better. But it's so tight. We could have been fifth this weekend and have a totally different conversation.”
Brown says improving on this year’s third place and closing the gap to Mercedes and Red Bull in 2021 will be a much tougher challenge.
The American also expects to see a resurgence from Ferrari after the Italian team faded to sixth place this season.
"I think it will be harder,” he said. “I think we got to keep our feet on the ground. You've got to expect Ferrari to come back strong next year. We know they're gonna have two very strong drivers, in Carlos [Sainz] and Charles [Leclerc].
“I think you got to assume they're gonna be right back where we expected them to be this year. So I think it's gonna get real tough from here on out.
"We've got everything we need now, especially with our new investors. Andreas [Seidl] has done an outstanding job. I think we're just getting started, but it's gonna get harder.”
Brown said the well-matched driver pairing of Norris and Sainz was key to McLaren’s resurgence, and gave the team an edge over Renault and Racing Point.
“If you look, [Esteban] Ocon came on strong at the end, but Daniel [Ricciardo] carried the team there.
“And then Sergio [Perez] is at a whole other level. And he carried the team there. So I think we've benefited from having two very strong drivers, as opposed to one.”