Certainly, storing them online is a poor answer, companies go out of business, their systems fail, you forget to pay your bill, not a 50 + year solution at all. In about 2000, my hard drive crashed and everythinng was lost. I had a one year old backup on CD of my images, and recent backups on floppy disks.
While it's true that many online solutions could be risky, I would trust the lifespan of Amazon over a consumer-grade hard drive. We've all had personal hard drives fail. I've also had hosted drives fail too. But the difference was that my online host had a backup system and restored everything without me paying any extra money or doing any extra work.
Ultimately, the best strategy is redundancy. For a home solution, it means arrayed drives (and a fireproof safe). But the level of cost and maintenance on such a system is formidable and you will be doing all of the work of maintenance, organizing, and syncing. And then, presumably, you will need to completely rebuild the system every 10 years or so. And without an associated online solution, you have only local redundancy.
For me, the big difference between a home solution and "hosted" solution is that the host will upgrade their equipment over the years. They will transfer your data and maintain backups. I would never suggest relying exclusively on a cloud host. Never. But let's recognize that storing data is what these companies do; and setting up an equivalent system at home is unrealistic for most photographers.
That said, as someone who has had hosted drives go down, I can understand people's wariness of using an online solution. And it's true that if the host goes down, those crusty backups will be the last line of defense. That was why, for super critical collections, I suggested having two online hosts.
It's all about redundancy and multiple points of failure. No single system will give a high level of reliability. All of these systems involve risk.