Past a certain point of accuracy in the reproduction, sound quality is pretty darn subjective. So for me, the difference is worth it, but you won’t really know if it is to you until you’ve tried a pair of M50's.
They’re pretty easy to demo now that the M50XBT is out. Many Best Buy stores have a demo pair of that model on display, so if you have any of those near you, you could try them out. The M50X has better bass response and a little bit more smoothness in the mids. You can see this in measurement graphs. Measurements are a good tool if you’re trying to decide how radically different headphones will be from each other in terms of overall tone and character.
Here’s a graph comparison from Rtings:
Headphones - 1.2 - Graph
Wireless Earbuds Wireless Bluetooth Running Gaming Noise Cancelling Earbuds And In-Ears Xbox One PS4 True Wireless Over…
The M50X doesn’t just have nicer padding and a more neutral sound. It’s also got a much better build with a nicer headband. It’s more adjustable both on your head and for wearing around your neck/storing/setting on a desk. And it also has a great detachable cable system.
None of those things is “necessary” in the most empirical sense of the word, and it just depends on what you personally want from a pair of headphones. From the way you’ve worded the question, it sounds like you’ve already decided the M20X is more right for you. There’s no shame in starting cheap and exploring more later! I’ve recently had a lot of fun with a $17 pair of headphones.
These Koss headphones have much bigger and nicer pads than the M20X is comfort is a prominent factor for you! Their sound is a bit more hollow and muddy in the mids, but they also have a great bass response.
So it all kind of comes down to what appeals to you the most! I can only share my personal experiences and I hope that they help.