With BSD alone, if you infringe on a Facebook patent then you are vulnerable to legal action from Facebook if they deem that you’ve infringed your patent. And regardless of wether you’d infringed or not, such action would still cost a lot of money to fight in court and would cripple most businesses.
People who claim it risks giving up their IP are ignoring the brutal truth that software patents are shit, and if you’re in the software business you’re pretty much guaranteed to be infringing someone elses bullshit patent.
The BSD+Patent Grant was designed to combat the patent trolls, but people lost their minds and now it’s gone.
The BSD licence is objectively worse than the BSD+Patent Grant. If you opposed it, then the only people you’ve helped are the patent trolls.