Facebook can work for crypto traffic, but it's not easy and definitely not for everyone, meta's policies are strict, and approval is the main bottleneck, to run ads, you need to get formal permission from meta, only licensed exchanges, regulated platforms, and some educational content qualify, if your project doesn't have compliance and licensing in order, it's pretty much a dead end, even when approved, ads with promises or passive income language will get flagged instantly.
The cost is another hurdle, crypto costs are volatile and heavily influenced by competition and strict compliance, this makes it tough to predict your budget, your best shot is using a compliant agency account with a high trust infrastructure, as many personal accounts get blocked quickly, focus on educating your audience, not just hyping your product, that's the strategy that consistently works.