if you want to work solo on some game 3 years hard, then maybe you can do small complete game, but are you going to buy animations/characters/statics or do it yourself?
If you want to make MMORPG alone, prepare yourself for 100 years of hard work.
My first thoughts were i can finish small game in 3 months, however it took me 1 year and it was so unfinished and unpolished - small game. i was working ~4hrs/day.
The best recommendatin is: dont start with mmorpg. First try something smaller and then you will see how much work cost mmo.
edit: https://www.gamespot.com/articles/rockstar-more-than-1000-people-made-gtav/1100-6415330/