There are some important practical considerations about filing foreign patent applications in addition to filing a US patent application. Here are some personal observations that individual inventors and small companies should keep in mind.
(1) Unless the invention is as revolutionary as Alexander Graham Bell’s telephone invention (which was so valuable that it was worth the cost of the foreign patent applications), the total legal cost in time and money of enforcing a foreign patent is likely to be greater than the licensing fees gained by enforcing the foreign patent. The US economy is quite large in itself, and the licensing fees gained from legally enforcing a US patent are more likely to be worthwhile. And it appears to be easier to find a litigation law firm in the US that will take a patent infringement case on a contingency fee basis (i.e., they get paid only if they win), compared to trying to find a litigation law firm in a foreign country to take a patent infringement case in their country on a contingency fee basis.
(2) If you foreign file, you will have to rescind your US patent application’s non-publication status within 45 days (assuming you requested non-publication when you filed). Non-publication of a US patent application (until the actual issue of a patent), because of several years delay in the US Patent Office, is almost always a great advantage in terms of avoiding a published US patent application giving foreign copycats a chance to rip-off your invention and file patent applications for it and sell it in the US and other countries before you even get your own US patent issued.
(3) As for the assertion that foreign patent offices (such as the European Patent Office) do a better prior art search than the US Patent Office – there is actually far more variability between the quality of a prior art search conducted by two individual patent searchers within a specific patent office, than there is variability in the quality of a search between the US Patent Office and a foreign patent office. In other words, after conducting hundreds of prior art searches ourselves and comparing our results to the official results, we have seen many inadequate prior art searches conducted by foreign patent offices too.
NOTE – There can be other considerations, and the observations made above are not intended or given as specific legal advice for your own particular case. So you should discuss these matters with your own hired legal counsel.