Prior art searching helps insure that you have the best understanding of the most relevant references that may impact your patent application.
A good search can inform your description of your invention versus the prior art and can aid in drafting more strategic patent claims. Without a search, there is a possibility of the Patent Examiner rejecting all of your claims in light of a reference previously unknown to the inventor.
There are resources for the inventor to do their own initial searching, but I always recommend a professional prior art search before you being drafting a patent application.
The one exception to this recommendation is when you have a looming public disclosure and you want to preserve foreign filing rights. In this case, the inventor needs to get a Provisional Patent Application on file with the USPTO prior to the public disclosure or risk losing all foreign patent rights for everything publicly disclosed.
Please reach out to me for a free consultation to review your options for obtaining patent protection for your invention.