Food is much much much easier to capture market share in
The Core Worlds collectively produce somewhere around 100 units of Ore, 90 units of food, 60 units of Organics, 60 units of Volatiles, and 50 units of Rare Ore, and market share is essentially (accessibility) * (how much your colony produces) / (how much the sector as a whole produces). Out of these five resources, then, Food is the second most difficult in which to capture market share; what it has going for it is that it is the most valuable single market (270,000 for Food, 140,000 for Volatiles, 122,000 for Rare Ore, and 117,000 for Ore) - but if you have a good mining target, that doesn't really matter, because you're going to be tapping at least two and possibly three (maybe even four, if you have an exceptional candidate, though decent Organics mining sites that aren't Habitable are hard to find), and you're going to be capturing a large enough share in each of them that the combined total exceeds what you'd get out of going for Food.
Assuming an accessibility of 100%, gross revenue for each of these resources, assuming a size-3 colony, is somewhere around:
Food: 6000 (-1), 9000 (+0), 12000 (+1), 15000 (+2)
Ore: 2340 (-1), 3510 (+0), 4680 (+1), 5850 (+2), 7020 (+3)
Rare Ore: 0 (-1), 2440 (+0), 4880 (+1), 7320 (+2), 9760 (+3)
Organics: 4667 (-1), 7000 (+0), 9333 (+1), 11667 (+2)
Volatiles: 0 (-1), 1700 (+0), 3400 (+1), 5100 (+2)
In my experience, finding Volcanic worlds with at least +1 Ore and Rare Ore and Cryovolcanic worlds with at least +0 Ore, Rare Ore, and Volatiles is generally easier than finding Habitable worlds with at least +0 Farmland, and it's not that uncommon that I find something like a double-Ultrarich Volcanic world or a double-Rich + Plentiful Cryovolcanic relatively close to the Core. Volcanic and Cryovolcanic worlds are among the most common in the Sector; Habitables, meanwhile, are usually some of the rarest, and some of them - like the relatively common Desert worlds - are often entirely lacking in arable land.
Food ... is fairly trivial to scale.
Autonomous Mantle Bore says hello.
Additionally, best mining worlds usually have pretty bad hazard ratings and this really affects the growth pretty badly. Hazard pay is a MUCH higher initial investment because otherwise the colony won't grow and even if it does, the hazard pay will eat all profits for a while unless you're willing to go size 3 everything.
This is a thread talking about setting up some "early" colonies for the express purpose of making money while avoiding triggering things that you're not yet prepared to deal with using your early-game (or maybe early-mid-game) fleet. Somehow, I don't think that the cost of Hazard Pay is a particularly relevant concern.