I almost kneejerk downvoted out of disagreement. Mega-corps are _a_ problem, but not the problem here, which you astutely pointed out.
Dropbox didn't/couldn't innovate beyond their core product is clearly the issue here.
Additionally, most of what I find that companies use Dropbox for equates to Shadow IT. Something that mature corporations ruthlessly eliminate.
I need quite a lot of storage for my projects and am up to a 42TB Enterprise NAS at home w/ Fujitsu helium-filled drives. Probably more than Dropbox customers would ever want to spend, but well worth it for me. Even if I didn't need as much storage, I'm pretty sure I would use the same product.
Access from all of my devices is easy as they're all on one VPN, including my phones.
That 70GB includes a modest collection of music from before the streaming era, a few videos, backups of old documents, Blender projects, Unity projects, a backup of all my photos from my phone (from the past few years), a couple archives of family photos (from the past few decades). I also back up product licenses and shell profiles there, for easy setup of new machines (which I highly recommend). The only important files that don't go in my Dropbox are my actual code projects, since those live on GitHub.
I use a whole lot more space than that when it comes to software, of course - Steam games, in particular - but there's no reason to put any of that on Dropbox because it can be trivially re-downloaded. I have 4TB of disk space on my desktop, but nearly everything outside of that 70GB is a glorified cache.
I honestly can't fathom how I would utilize 42TB of backed-up data storage, unless I decided to start torrenting. And anyway, a local NAS won't do me much good if the house burns down or gets broken-into. A cloud storage solution that presumably gets replicated across multiple data centers, and also mirrors local copies on all of my devices, is the most durable data storage solution I can imagine.
I prefer having access from my devices without the replication.
I do back up my Steam library, btw, because occasionally they remove games. That folder is at about 4TB.
//inside joke if you dont know.... Data Hoarders only every have Linux ISO's....
For most people, consolidating many services into one is just more convenient, even if it means using a "good-enough" version of that feature.
E.g., digital displays are a "feature, not a product". End-users get value out of digital displays on their thermostats, microwaves, etc., but no end-user buys a digital display themselves, thermostat and microwave manufactures buy them.
I think the problem with Dropbox is that it's become too easy for product companies to build data syncing themselves.
Even if you eliminate Microsoft, Google, AND Amazon from the discussion, the list of alternatives is endless.
Synology and QNAP both have a "free" sync and share client. WD, Seagate, Samsung, Apple, not to mention the open-source options out there. Do the big 3 put MORE pressure on Dropbox, sure. But they never pivoted. Just look at a company like Druva - we used them forever ago as a file sync and share, and now they look very, very different.
Dropbox's problem isn't mega-corps or "big tech getting too big", it's that they didn't or couldn't innovate beyond their core product.