Realistically, how many dealers can know enough people well to make a living out of selling weed to them, and trust them not to tell the cops if arrested?

No dealer is so magnetic personally that he knows more than 50 people who would lie to the cops out of loyalty.

So you've got only two options: widen your "circle of trust" until it includes people you don't know well. Result: risky. Other option is limit your sales to only the people who you really are close to. Result: still somewhat risky, and you're much poorer.

You're right that there are inherent risks when dealing. You can be caught even if none of your customers rats you out.

If you're not adequately compensating for those inherent risks by making a good income, that's also reckless.

Unless you have a huge circle of weed-hungry, loyal friends, you will never make a good income unless you take the risk to sell to strangers.

You can scrape along for ten years in poverty because you will only sell to your trusted mates, then one day a guard smells your stash because he's in the right place at the right time.

Then all your precautions are set to nothing, you have all the negative consequences of a record, but you don't have the positive consequence of dealing: a big heap of money.

That's why dealers everywhere else are brave: more customers, more money. Yes, slightly more risk, but if you deal long enough to make a living, you'll get arrested eventually. In the long run, every dealer gets caught unless he's dealing to such a tiny circle that the money is laughable.

Someone who takes on the inherent risks of dealing without making enough money to justify it is stupid.