Organizations, teams and individuals are obsessed with doing things themselves when a similar or better solution is already available elsewhere. Thinking that if you have to get it done right then you have to do it yourself is no less than some kind of obsession.
I have seen people rejecting better ideas just because they did not contribute in the ideation. Organizations spending enormous amount of effort in developing internal systems when a majority of what they want is available off-the-shelf. Teams trying to solve technical problems themselves when a solution is available already in other teams sitting under the same roof!
One of the possible reasons for ‘not invented here’ syndrome is that people find it hard to accept (or trust) something that they have not created or contributed to. Fear (and insecurity) of using someone else’s solution may also be a reason. Sometimes, people just don’t know that better solutions are readily available.
In any case, valuable time is lost, money is spent and opportunities are missed just because you choose to invest your effort instead of reusing what is already available.
In lean terms, this is a huge waste.
Because “not invented here” is almost the same as “lets reinvent the wheel”, unless there are strong and legitimate reasons to invent a newer kind of wheel.