@len97010 Yes, the cambridge analytica scandal was centered around some people inadvertently granting total access to these data scraping apps and being able to also access their friends' data. The smaller the group of people you share with online the safer you are.
@jannyw4011 WhatsApp pictures are encrypted so it is safe.
Facebook and instagram are also safe if you only share with friends. Public forums like reddit are where the issues lie.