And there's a vast number of pilots in Elite with many times more credits, ships and engineering materials that simply cannot play in Open while doing BGS, or in CGs because they simply don't know how to evade (let alone counter-attack) a player CMDR with murderous intentions.
And that's because they've chosen to stick to the easiest gameplay mechanics relying on "as long as you build an enough powerful ship, you're unstoppable"
But that can be fixed. It took me a long time, and i'm still learning, and i'll be still learning for some more time, but i can now take on stuff that it was unthinkable i could take on before.
It's the same with thargoids (and maybe even easier)
Don't know how old you are, but two decades ago (and backwards) most video games were build on the rule of "defeat this boss or you won't get past here". And whoever wanted to get past there had no choice but to experiment, fail, get better, learn, fall, get up again... until they, solely by their own merits and all the experience they got from their mistakes, were able to defeat the boss. AND IT WAS REAL SATISFYING.
Contact the best mentors you can, listen to their advice, and go confront those caustic cauliflowers. No matter how many rebuys it takes, you'll get to where you want to be eventually.
Good luck.