Can you really be selfish?

Simplicity

One of the things I believe strongly in is “nobody can take better care of you than you.”
To some, this initially sounds selfish.
Seeking my desires and needs must mean I do so at the expense of others, right?
I mean, that’s when others call you selfish.
The interesting thing is … the term selfish is only used when someone else doesn’t want you to do or not do something they prefer.
So can you really be selfish?
What do you think?