"Massive fanbase" refers to a large group of dedicated supporters or followers of a particular person, team, brand, or product. These fans can be enthusiastic and passionate about whatever or whoever they are a fan of. Full definition
I still think it's a tad easier to get rid of Wenger, because of Arsenals massive fanbase, it's difficult that we'll soon start losing rapid amounts of money forcing Kroenke to sell. (justarsenal.com)
Massive fanbase; biggest sponsorships; tons of cash, CL football year in and year out; etc, etc, etc. vs One season in EPL in club's history. (justarsenal.com)
They also have a massive fanbase, particularly, across Eastern Europe. (eplindex.com)