In fact the two main reasons are
(1) taking off when you should have stayed on the ground
(2) pressing on with Plan A long after a switch to Plan B was called for.
What you are trying to say is that the main reasons are
ATTITUDE TO AIRMANSHIP
Your own personal attitude is usualy the start of the error chain.
£5,000 of handling skills will not improve your chances of survival if you fly into a cloud with a hard centre.