Fair warning before you take all this 'be patient' advice, robigo (& friends?) may finally get killed off after the next big update:
https://forums.frontier.co.uk/showthread.php?t=251942
As for my own road to riches (well, assets), put it this way. I'd been playing since the preview program - at the point of hearing about robigo, my biggest ship was an Asp & I'd accrued about 70mil in the bank from doing a bit of everything. My dream back then was a multipurpose Python but I was still only halfway to affording it. After a couple of weeks doing robigo, I'd more than doubled my money and the Python was mine.
I then tried my hand at trading. Trade routes in a 200t Python bought me a 400t Annie. At that point, trading profits over time seemed about level with robigo. The Annie then funded a bunch of other ships including a 720t Cutter, bringing me finally to ten times the hold size of my beloved Asp - this is where trading starts to properly outdo robigo money, but it's a long grind to get there.
tldr, if you want a head start to the annie, maybe hammer robigo while you can. Cause without the big ships, making big credits can otherwise be a slow process.