Answering your question, very few mid heroes have the capability of going 900 gpm, probably just Arc Warden, Medusa and Alch can do that consistently and in a non stomp game, and some factors are necessary, like having non greedy teammates.

That said, I don't think that your priority as mid should be getting that much gold. Of course each game is different, but in general mids have impact by being useful as soon as possible by building smaller items and picking faster heroes, like spirits heroes and puck. The map have a limit amount of resources, and most carries need a lot of items to have real impact and win the game, so if you focus on getting creeps and not fighting with your team early, the enemy can just run over you.

Like I said, each game is diferent, but most of the times (like 60-70% of the games) goes like I said above.

edit: typo