Since unions helped to end practices like child labor and what amounted to indentured service, I’m not sure you know what “tragic” or “long term” means.
If what you mean is more like “what have they done for us lately”, you should probably just say it and start that conversation instead
That underscores the point for me though — the company and shareholders both take a back seat to the well-being of "the rest of us".
If you're looking for something much closer to home, look at how in the past half century unionized corporations were forced to take over pensions, and how they're doing now because of this. Pensions are a financial product, which should be paid for by each employee - quite likely with supervision and safety net from the state. Putting it on the employer's tab turned out to be more or less giving away the future of the company. And that's pretty much 100% on the unions.
That said, there are a lot of reasons why traditional defined benefit pensions aren't a good match for a lot of jobs today. I have one (for a non-union job) but it's mostly a positive because I'm sure I never gave it a second thought early career when I was earning into it.
Or would you like to talk about the long term results from actions of unions last year?