Instagram likes are a very valuable metric. It's a part of user experience so important
that despite attempting several experiments to hide likes, Instagram returned to their
original interface.
There are a number of reasons why. They show followers engagement
which is an important metric for advertisers. Likes display your popularity compared
to other users. Posts with many likes tend to perform better by signaling to users that this post
is worth viewing.
The background for why many people find likes important is deeply psychological and you
could spend a lot of time debating reasons for why it is so. The most important takeaway
here is that getting likes is fun. It's what made us build this network.