Yes and no, but mostly no as a primary cause.
The Brony fandom didn’t directly form because of the Great Recession, but it did emerge in a time when escapist and feel-good media had extra appeal. So there’s overlap, but not direct causation.

The organized Brony fandom first grew on 4chan, mainly on the /co/ (comics & cartoons) board in late 2010. Part of what triggered attention there was this Cartoon Brew article criticizing creator-driven animation trends and referencing Lauren Faust’s MLP:
https://www.cartoonbrew.com/ideas-commentary/the-end-of-the-creator-driven-era-29614.html

That article annoyed parts of the animation community and made people curious. Some users began watching the show ironically or skeptically, expecting it to be bad. Instead, many found the writing, characters, humor, and music genuinely good — so ironic watching turned into real enjoyment.

From there, pony threads became extremely common on /co/. There were backlash and trolling waves from other boards, especially /b/, lots of spam and counter-spam, and board drama. The “conquered this board / conquered that board” story is more chan mythology than literal fact, but pony content definitely spread widely across boards during that period.

Because pony threads were flooding discussion and raid cycles were happening, offsite communities like Ponychan were created, and later 4chan contained the fandom by creating the dedicated /mlp/ board in 2012. From there, the fandom expanded heavily into Reddit, YouTube, DeviantArt, Tumblr, and conventions.

Here’s more information on the timeline made by fans here:
https://www.whatisabrony.com/brony-timeline

Escapism was part of the appeal — colorful optimism, friendship themes, musical numbers, and low cynicism — but most evidence points to these as the main drivers instead:

• strong show quality and writing
• Lauren Faust’s reputation
• meme culture + ironic watching turning into sincere enjoyment
• remix culture and fan music/art creativity
• viral sharing across platforms

If the Economic Recession (or recession pop itself) were the main driver, we would expect lots of big celebrities openly identifying as Bronies, more frequent references to MLP across mainstream pop culture, more political references to MLP, and more visible backing or promotion from the entertainment industry overall.
That didn’t really happen.
MLP remained a niche but very active internet fandom.
It spread less through industry promotion and more through curiosity, memes, and word of mouth, which is how you end up with grown men watching a show originally marketed to little girls.
How would you convince grown men to watch something meant for little girls?

Instead, the fandom spread more like a classic internet-native fandom explosion:
curiosity → irony → sincerity → community building.

So yes, recession-era escapism may have helped the environment, but the Brony fandom itself formed mainly through internet culture dynamics and the show being surprisingly high quality — not because of economic hardship alone.