Let's look at some numbers. Ukraine, a largely agriculture country, is one of the strongest possible cases for your thesis. So consider net Ukrainian raw materials exports: <https://wits.worldbank.org/CountryProfile/en/Country/UKR/Yea...>
Around $18 billion in 2019. To gain partial control of that revenue stream, Russia has largely smashed up the military it spends $50-$60 billion a year on. It's not a good trade.
You might protest that land also has factories and such on it, and that's true, but today many of those factories look like this:
<https://gdb.rferl.org/07520000-0aff-0242-a90c-08da3a5a2c06_w...>
Launching wars of aggression is a bad idea because killing people and taking things that don't belong to you is wrong. But if that fails to persuade, recall that it's also a financial catastrophe, for both sides.
(Edit: formatting)
With my deeply cynical hat on...
I mean, if they keep the territory (which seems unlikely at this moment), they get that revenue, so good for them?
They also got to clear out their stores of old munitions, and run a sales demo for newer munitions. Might have been a better demo if the campaign didn't go sideways, though. Either way, lots of business for domestic producers of munitions to resupply.
Where a whole bunch of natural gas was recently discovered (Crimea specificly).
To be clear though, i'm not saying that its always direct. Plenty of things can be strategically valuable but not instantly translatable to $$$. Even businesses don't always do things for the short term profit exclusively - sometimes long term matters.