Don’t write your own ORM, NHibernate and Entity Framework are probably faster, more secure and less buggy than anything you could write.
Don’t manage your own servers. Let Microsoft, or Amazon, or Google, or a myriad of other providers do it for you. Let someone else monitor the patch list, recover from failures and continually roll out new hardware.
You own your dependencies, but sometimes that’s better than owning a half-baked, home-brewed alternative.