Hello, thanks for your question.
I only use Facebook and Tumblr for social media.
My thoughts on social media to create an online presence is very negative. By all means, I am also guilty of this – I post updates on Facebook and write on my blog here, which is linked to my Facebook. I keep things very honest on Tumblr, but most of my past (1+ years) and even many of the recent (<1 year) posts on Facebook are narcissistic, just like 99% of the posts you will ever read.
In terms of friendships, Facebook helps me keep in touch with friends and acquaintances. Most of my closest friends are people I see once or twice a year. It helps seeing what they look like, what they’ve been doing, and messaging them in a convenient way.
In terms of businesses, I’m not sure what you’re referring to. I think social media can harm the chances of one getting a job if 1) he or she is careless and 2) the employer is meticulous.