Why is in house ERP may not be the long-term solution?

It eats up a lot of resources and requires a large investment into the technology and skills needed to keep the ERP application up and running. In-house ERP systems are way more difficult to maintain and upgrade as there are only a few people who know how the system was developed and how to use it. There are serious limitations or hinderances due to internal resource knowledge & capacity. In-house developed system will often turned into a legacy system due to limitation in skillset or technology. It gets outdated for a much longer time and not as robust as the standard ERP.