I don't think the nra should have footed the bill, but they should be doing SOMETHING. By something I mean things other than supporting bump stock bans and "gun violence restraining orders". They should be organizing rallies even if they are not paying for them. What exactly are they doing aside from paying off lawmakers and the occasional lawsuit?Calling is probably second best to showing up while in-session, but that's not an option for very many. Letters work about the same (not emails, actual snail-mail). Calling worked wonders in 2013 after Sandy Hook.
That being said, you are right that sometimes it's important to show numbers. The problem is the Second Amendment doesn't have any billionaires ready to throw down the hundreds of millions needed to match Blomberg. The NRA would end up broke trying to match them for even a year. In 2016 Bloomberg gave every single one of his organizations $50 million in funding... More than the entire budget for the NRA that year.
As these organizers found out, free speech is expensive of you want to do it at a large scale. Look at the two bills mentioned here, about $7000 each for police OT and porta-potties. Bloomberg's groups setup rally's in 800 cities. That's over $11 million for just these two basic expenses. That doesn't count all the extras like busing people in, pre-printed signs, tee-shirts, paying 'volunteers' to act as marshals, lining up speakers and renting equipment. And you can be sure the costs were a lot higher for everything in cities like D.C. or NYC.
People complained that the NRA doesn't foot the bill for this kind of stuff. That $11 million for permits and honey-buckets would be the NRA-ILA budget for the year. Yet because they didn;t go bankrupt trying to 'keep up with the Bloombergs', they don't feel they should join the group, or make a donation. A vicious circle where we eat our own. Something the gun comminuty seems pretty good at doing.
I'm sure all the other actual rallies and marches probably did pay these kinds of fees. But they have all kinds of funding available to do it. The permits in DC ($50,000 plus from what I saw) were paid for by the American Teachers Federation, so it was no surprise that teachers all over the US were pushing their students to participate.
You can bet ANTIFA didn't pay for anything but to ship their paid thugs to attack legal rallys. And the BLM folks blocking highways were obviously illegal.