Another way to phrase that would be that he got crazier the closer he got to 'End of Time', yes?
Honestly though, I have a very patchy knowledge of classic who so I'm not all that familiar with the Master's pre-McGann appearances. I think the only one I've even seen was Logopolis and I could barely follow what was going on. That said, my impression is that he's always been a megalomaniac of some type or another.
He's basically Voldemort, right down to killing off relatives and finding ways to continue his own existence that involve the use of his people's historical artefacts. XD
I personally think Ainleys portrayal is underrated, especially considering how the in universe explanation for him went....