Is playing with friends who use foul language and joke around with insults and curses considered a "gathering of evil for devils," and should one abandon it despite the scarcity of remaining friends and the fear of being perceived as an extremist, and how can one find a middle ground in this matter?

What your friends are doing – cursing, swearing, and uttering words that displease Allah – is forbidden, because it is among the harvests of the tongues that cast people into the Hellfire, and joking does not make the unlawful lawful.

So, beware of befriending such heedless individuals, for a person is influenced by their close companion, and staying away from bad company is salvation in this world and the Hereafter. Every friendship for other than Allah will turn into enmity on the Day of Resurrection, except for the friendship of the pious.

Your presence with them in a state of disobedience is forbidden, even if you do not participate in it, because it signifies approval and endorsement. If you are unable to forbid the evil, then you must leave their gathering.

Doing this is not extremism but rather praiseworthy moderation that aligns with the Sharia, and the definition of moderation refers back to the texts of the Sharia, not to whims.

Playing football is permissible under certain conditions: that it does not distract from an obligatory duty, that it is not accompanied by forbidden acts like cursing, and that it does not turn into a waste of time.