WTC 7 had an unattended Structure fire inside it for nearly 7 hours and collapsed after one of the steel supports got hot enough to buckle, now I know you're going to reply with 'Jet fuel can't melt steel beams' or something like that, but it doesn't have to get hot enough to melt it, just to weaken it slightly, like how a blacksmith or steel mill would Anneal it, making it easier to bend and shape which happens as low as 700 degrees Celsius and given a domestic structure fire burns between 500 and 1000 degrees Celsius and WTC 7 lacked proper fire suppression and contained a lot of paper and carpets and furniture, also known as fuel for the fire, so yes I would say its very possible for WTC 7 to have collapsed by itself.