I've lost a lot of personal data that has been an only copy on USB[1], also other external HDD, CDR(W), floppy discs (5¼ as well as 3½), internal HDDs[2], DAT cassette or even C90. You name it..., hardcopy printouts even. Some 'important', a further amount not nice to have lost[3] and much more that probably isn't worth a hill of beans but leaves regret for not knowing.
That time when the spinning disc no longer spins (or audibly spins but appears to think it doesn't) or the thumbdrive suddenly goes "device not recognised"... Or clearly fell out of my pocket/got left behind somewhere. Occasionally moved data wrongly or failed in some way whilst shuffling. Or the paper got too wet to read[4]... This is the situation the Cloud is meant to help with. A regime of industrial-strength backups (backup of data, backup of hardware, backup of backup-site, ...backup of access method?) to mitigate all kinds of failure-modes.
At least, of course, until something unforseeably unforseen happens ("I'm sorry, customer, everything you uploaded between March and August seems to have been... misplaced?") or equally forseeable but still your responsibility (your main synched device fails out of the blue, you can no longer remember your saved cloud-login details to and you forgot to update your backup email address when you changed ISPs two years ago). The removal of so many other single points of failure is still subject to failures, and it of course won't take the complete failure of civilisation to highly inconvenience many people who take the Cloud as a guaranteed element of data security[5] merely through faith.
Not that I actually practice what I preach, sufficiently. But duplicate your backups ("Grandfather-Father-Son") and distribute across different 'locations' (physical or online), which of course you must attend to updating regularly (or, preferably, frequently). Pre-encrypt that data yourself, whatever apparent protection[6] is already inhetent; choose your own chosen level of precaution, in this regard, even if it means keeping a PGP t-shirt somewhere and learning how to follow the algorithm through with pencil and paper. And, finally, accept that things get lost/stolen anyway. GoogleDrive, 23AndMe, etc...
Oh yes, I've lost much data. With valuable lessons learnt, or unwisely ignored. (Professionally, too, but those are stories for another day/elsewhere. And thankfully that quantity is dwarfed by the amount I've been actually involved in keeping safe.) I wouldn't consider the Cloud as a panacea. Though perhaps it can be wisely made use of, as it happens to nebulously (NPI!) exist as an option.
((But wasn't the original reference to the Cloud more to do with Cloud Computing? That's a significantly different animal, with further arguments for and against.))
[1] Not yet SD, as I haven t really used distinct SD storage.
[2] Or equivalents, which may indeed be functionally similar to SDs.
[3] e.g. painstakingly recorded/saved information that means little except for the gathering, which cannot be repeated, merely resumed with a gap.
[4] The one fate I can't currently recall ever finally killing electronic data, though of course it is a viable one, as would be loss in housefire and other 'physical' disaster.
[5] Which, as I tend to say more often than I think is decent, is two-part: a) Not to lose access to your data, b) Not to lose control of your data. Whether the entirety of your 'private' records end up in the hands of criminals(/rogue AI) is something now far beyond your control, compared to making your own individual arrangements with your own rather limited risks.
[6] Active encryption (encapsulated) or obscurity (hidden behind a keycode). Painstakingly carved into a remote antarctic cave wall using meaningful glyphs of your own design or pervading all the world's major pop-songs as a subcarrier-wave only comprehensible by one who understands the steganographic method sneaked into every major recording studio. Above all, don't just do what everyone defaults to (or only that). Use your own wits, insofar as you have confidence in them, to make yourself at least slightly higher than all the other low-hanging fruit that may at some point become ripe to be feasted upon.