When I first started out in timber felling back in 1982, it was officially the most dangerous job you could do. If you had all your fingers by 21 you weren't trying. People died every month. Understandable really, a chainsaw is a nasty bit of kit. Knowing how to use one safely is not simple and only a fool assumes he is safe. I saw my first death three days after I turned 16. No chain-brakes back then; kickback and a powered cut to the carotid artery; man died in less than two minutes. I still remember it like it was yesterday - I was the only first aid trained guy on site because I had been in the Scouts. I used my shirt as a pressure bandage - although we didn't call it a pressure bandage back then. It's not nice, being unable to do anything.
Safety kit, training, techniques and rules now mean that tree felling is one of the safest industries in the UK, people rarely die. The people that do still die are those that haven't got the training, the kit, don't know the techniques or the rules...
Trees are heavy, grow funny, have funny stresses due to grain, species and growth habit. Chainsaws don't cut, they rip and tear. They remove a quarter inch width of flesh in a clean stroke. Most folk use mineral oils so if you don't bleed out, you will have major vein and nerve trauma exacerbated by the mineral oil - say hello to Mr Gangrene...
You attempt to move that tree and it goes wrong, someone will get hurt or die. That will be your fault. If you have ticked all the boxes then the man with the funny wig will say you did everything you practicably could. If you haven't ticked the boxes, then you will need soap on a rope. Simples