Do you know they are using them to sell you services and goods? That they are mining those photos and selling the insights gained to advertisers and political campaigns? Possibly straw men from foreign governments? That like Facebook they are mapping who you know, where you know them from, and how deeply connected you are to them? If that's not terrifying I don't know what is.
You retain almost no control of data you upload to any cloud service. And the more data you put on the cloud the less freedom you experience in your everyday life because your choices get made by a marketers algorithm or your location services.
None of the "free" services are worth anything if you value your privacy and freedom.