@born2ollie : In simple terms, the risks
@TheJollyLogger is talking about (as I understand them) are:
The tree is leaning, so the wood on the "tight" side wants to pop and can smack a person standing near it, which with a short bar would be you. It could potentially drive your ribs from the front of your chest to the back near your spine, flattening you pretty much instantly. The speed and force the tree has is unbelievable--until you see it.
The tree has a big split, so once the wood holding the tree up is cut the thin walls around the outside of the tree can crumple and blow out, throwing wood at you--kind of like throwing a solid wood stake at a vampire, but in this case it's you getting impaled and are not in a movie.
Limbs above you are always a danger, they can break off and hundreds (or thousands) of pounds can mash you into the ground like a nail hit by a huge hammer. Imagine a bowling ball up there being dropped on you, and that's only 18 pounds or so--this is perhaps a thousand or more pounds per limb and huge.
The problem tree you're trying to address fell into another tree, so the risk is increased because when they separate one is likely ripping limbs off the other and launching them. They fly unpredictably, so it is pretty dangerous.
I do landscaping and can tell you from experience twisty trees are unpredictable, and I don't like them. Every time I study a tree and think I have all the forces figured out there's something unexpected somewhere along the way. There are some things expensive safety gear doesn't protect you from, twisty trees can find a way to bite you, and hospital bills are pretty expensive.
There are a bunch of other things that can and probably will go wrong, those haven't even been discussed. They can get costly, but at least don't end with a trip to the hospital. (Usually.)
I'm
not an expert, some of these guys are, and when it comes to cutting trees, "safety" isn't one of those things you ignore like in daily life, in this case ignoring stuff can get you killed pretty easy, which is why the pro tree guys use an abundance of caution. I'm not trying to get preachy, just saying there's a lot of stuff that can go wrong, much of it hurts.
I'd say it's probably best to let a pro tackle the risks. You're going to have to pay for their insurance premiums and equipment costs and such, but they earn it, and it's money well spent.