Basically, the Broncos were hated from the get go.
We were invited to participate in their competition to help expand the game but the Broncos weren't happy to play by their standards and were constantly finding ways to improve themselves on and off the field.
This caused two things to happen. Resentment and higher expectations. The sooner we couldn't meet the latter, the boots would naturally come in from all and sundry.
We also clashed heads with the NSWRL administration all the time over petty matters. This didn't reflect well on the club but there's two sides to every story and the one that's rarely ever told is that they didn't want our administration to win the liscence and had their own choice in mind who didn't have the support of the Brisbane community. They kicked the shits and started doing things just to piss us off. For instance, the Gold Coast weren't originally planned for the 1988 expansion but were given a license not long after they realised they weren't going to get their way with Brisbane, gifting it to a failed Broncos bid and to make matters worse, to tip-toe around their location exclusivety agreement with Brisbane, they based the Coast in Tweed Heads, fulfilling their obligation that the Broncos were the only Queensland team in the competition. On top of that, they also handed the Coast & Newcastle significant grants which the Broncos weren't offered. This created bad blood and it only got worse with issues like the judiciary who were as inconsistent as ever.
Even in Brisbane, there were a lot of BRL loyalists who didn't want to support a Sydney team and just never took to the Broncos. This group, that I like to call the anti-Broncos South Queensland fans only grew when moments like Super League & Lewis being sacked took place.
From there, every club has their reason really. You can't compete in a competition without pissing somebody else - at least not if you're doing it right. With the Dragons, not only did we beat them in consecutive finals but Alfie also got up after the game and sang that famous little diddy. Either way, probably not the most classy thing but what Dragons fans don't realise is that Alfie was under the impression Brian Smith had all these really derogatory opinions of the team and they really got on the nerves of our players. As it turns out, it was doctored by Bennett and proved to be one of the main catalysts behind our second premiership.
You then had Super League where both clubs were entrenched firmly on each opposing side and when news broke that one of their key players in Gorden Tallis was going to sit out the entire season they weren't happy at all, especially when they made it all the way to the Grand Final without him.
And all sorts of incidents along the way. I think a big part of it is that there are a bunch of Dragons fans who live in the South East and don't enjoy living behind enemy lines so to speak and having to put up with all the propaganda.