This arrangement buys you one thing only: you're always first to market
Which isn't enough to guarantee wealth. Here's the deal:
- Wine requires a nice grape - which has nothing to do with your magic.
- Wine requires a nice environment - which has nothing to do with your magic.
- Wine requires correct storage - which has nothing to do with your magic.
- Wine requires time to ferment - this has to do with your magic.
In other words, you have all the same problems of every other oenologist, but you can speed up the fermentation process (age the wine more quickly from the perspective of the wizard's reference frame).
And that means you can get it to market faster. But you don't have any more of it and you still need everything else to make good wine and one you've sold your lot — you're done making money.
What about bank interest?
No, not really a solution to the problem. Yes, you're getting the money into the bank sooner, but that's a benefit for only the first deposit. Every deposit after that occurs exactly one year later because you still need to grow the grapes, etc. So, you make a couple of extra bucks on the fist deposit's interest, but that's it.
OK, but being first to market must count for something, doesn't it?
No, not really, because everybody else is out there still making wine. They may be taking the traditional route — but there's still their wine to be purchased. They could always release last-year's wine in competition with your wine this year.
So, how do I make an absolutely offensive amount of money with wine?
Your magic multiplies the amount of wine you have so that you have more wine to sell.
Your magic improves the quality of the wine so you can sell it for more than your competitors.