I cut some of my trees myself, but only up to where my ladders will go without being extended too much AND provided I can reach them comfortably with the chain saw. Some trees are really hard to cut, such as Hawthorn and elder, whilst others are a lot softer, like Willow. It can be really difficult handle a chain saw at height and a precarious angle.
I won't tackle anything too high, there's way too much risk for personal injury. And if I was in a semi in a residential area, there's also the risk for third party damage, i.e. neighbours buildings or cars.