How common is it to change your masters/PhD thesis after already starting work on it?
universal
>>9065225
For brainlets.
teichmuller
How common is it to simply drop out of it?
>>9065224
If you're not too far invested in it, <1 year of work, and you can find another advisor to take you on, it can be done. Most people don't, because they know what they want to do in life, but for those who find it isn't what they expect usually find out pretty quickly and can make the transition.