carlo ponzi
You can be great without being good. In fact, you can be great despite being bad.
Bad of course has two senses - "lacking morals" and "lacking skill".
You can be great despite lacking morals as long as you get caught. History is far harsher on villains who get away with their misdeeds.
You can be great despite lacking skill if a) your lack of skill is total, utter and complete and b) what you’re attempting but lack the skill to pull off is upper case huge.
Someone who incorporates all of this – total lack of skill in some huge endeavour which is also immoral and gets caught – I.M.H.O. is great despite being bad.
Today’s great Italian is great in this way. Today’s great Italian is Carlo Ponzi.