Its' not whether the big ships are worth it, to be honest: they're a tool and, therefore, as good at the person using them.
There's a fashion, currently, of rushing immediately to end-game and banking billions and buying the super-big ships and ticking all the boxes and feeling like a proper badass. Except: without experience in combat, engineering unlocks and time spent playing around with ship builds as you work through the game, you're not going to understand how to put those big, shiny, expensive ships to good use. Or any use at all.
People can play any way they want, but rushing to the end before you've even learned to kill stuff with reasonable confidence says to me that you should probably work a little more at the basics if you want your Big Shiny Endgame Ship to really make you feel like a badass.
As I said before, your shiny ship is only ever going to be as good as the player who outfits, engineers and flies it.
*Edit for context: I've been playing almost exactly 30 months. And it was just 2 days ago that I bought my Federal Corvette. Sure, my play has been sporadic, but I've been perfectly happy flying about in a vulture for the longest time, with a python as back-up for bigger, longer hauls. Those two ships have served me faithfully and taught me a lot about heat and power management, outfitting (specific and multi purpose), engineering with specifics in mind and, most importantly, how I enjoy flying.
I've tried a whole host of other ships, including the ever-popular FDLs, 'condas and Asp Xs and didn't get on with any of them, even after engineering and outfitting them in a variety of different ways. With all that said and done, I've known for a long time that the Fed 'vette was going to be my ultimate ride. But I felt in no particular hurry to get it and enjoyed getting to know a krait (or two) in the meantime.
Now I have the corvette, I know exactly what I'm doing with it. I'm confident on how to fly and fight with it, how to outfit and engineer it for the best performance I want given the purpose I have in mind for it.
This isn't to be a smart-arse lecturer but to present you with an alternative option to all those "NEWBIES START HERE!" one-play-style get-rich-fast videos that seem to breed like fleas on a damp dog at the moment.
Take your time. Learn. Fuck up. Die. Farm mats and waste them. Buy expensive ship parts and forget which station you stashed them at. Turn ADC off and get stuck in the envelope. Spend almost all your cash buying and outfitting a ship you end up loathing 15 minutes after flying it for the first time.
More importantly: Have fun.
"Drink fast, die young"
"You may ask who was wearing the bow tie; me or the shark. The answer is: YES."