the biggest threat to bitcoin is lack of scalable self-custody. if you use IOUs instead of bitcoin you're not using bitcoin. too much risk.

actually I take it back. the biggest threat to bitcoin is people saying "it's okay to use a custodian." the community doesn't tar and feather these individuals enough.

actually actually it's probably the dwindling block reward, but everyone is too cowardly to even talk about what that's going to do.

many much bigger problems than "spam"