Dzitbalchen wasn't a great, just a 'normal' dragon, and they CAN be brought down by people who have enough force.
But as for why people are like "Oh shit, dragons"? Dunkelzhan was LEGENDARY for his machinations, and was still screwing with the world for DECADES after his death through his will. Ryumyo is basically one of the major behind the scenes powers in the Yakuza and MCT, and everyone knows it. Lofwyr took over Saeder-Krupp and the first anyone knew about it was when he stepped in, told everyone he was the majority shareholder, and kicked the board to the curb. Ghostwalker shows up, and proceeds to kick the asses of several national militaries for days before the Draco Foundation stepped in to convince people that it would be best if they all just accepted him as overlord of Denver. Hestaby did much the same when CalFree and Tir Tairngir were fighting and got too close to Mt. Shasta. And then there's Amazonia.
Sirrurg was only brought down after an Immortal Elf helped Aztechnology complete a magitek superweapon and lost almost 1/3 of all of Aztlan and Aztechnology's combined forces ramming it down his throat. AND HE STILL WASN'T DEAD!
Lofwyr tanked a ritual magic attack in the middle of a dragon fight and still won.
And that has nothing to do with how dragons can manipulate things behind the scenes. Dragons are schemers, never forget it. They are at their LEAST dangerous when you're trying to deal with them with direct violence. It is telling that the only times anyone manages to defeat the great dragons, it is because they were using the resources of a megacorp, or they were immortal elves or fellow dragons.
Sure, but most of the stuff isn't known to the public or even runners.
And you think what the Vory and Yaks are other mobs are up to is common knowledge?
What you are missing is the very fact that NO ONE knows what the dragons are up to, and there is no way to know!
You know you are working for the Vory or the Yaks or the any other Mob gang by the very way they do business... They want you to know who you are working for! - its part of their power.
But a Dragon? (let a lone a GREAT Dragon!), They don't come and sit down and chat about the job they want you to do. They hire an intermediary to do the meet.
Their plans are also highly involved and detailed, to the point that even Niccolò Machiavelli's head would explode in trying to figure out what they are up to.
There are several stories in the older editions (2e and 3e) where some runners thought they pulled a fast one on a dragon.... only to find out that everything they did, right up from the rumor that "dropped into their lap" right on down to the fence that bought the stolen goods where ALL part of said Dragon's plan....
And those Runners that thought they pulled a fast on a Dragon and made off like bandits? they ended up on Interpols top 10 international terrorists lists and where promptly hunted down and killed by LE.
And the Dragon? He made billions, even after he lost millions.... And other then the shadow community, who pieced it all together after the fact, knows onw knows which dragon was responsible (Lofwyr, Aden, and Hastby are the favored choices)
And then there is the Runner that "pulled a fast on of Lofwyr" in 3e..... Found dead in his bed a year and a day after the run (and bragging about it)....