Barriers to entry.
Wikipedia definition: "... is a cost that must be incurred by a new entrant into a market that incumbents do not have or have not had to incur."
In our professional pursuits we see barriers everywhere. Some of them are real barriers, and some of them are just perceived barriers.
For example, the airport sign above is designed to send the message "stay away." But, lets look closer at this message. The phrase "Airport Property" catches my attention. That really doesn't make any sense, because an airport can't really own anything can it? Furthermore the airports in the US belong to the people. Yes you're trespassing if you're not an authorized user, but that's not the message on the signage. If you have an interest and you just walk away, you've done yourself a disservice.
Continuing with the aviation theme, if you simply take an interest in aviation, and regardless whether you're a US person or a non US citizen (it really doesn't hinder you) and you've got a clean background, then the door is wide open for you to participate and become an authorized user (commercial or private pilot, supplier, mechanic aviation tech, etc). There really isn't a barrier there, you just have to make the decision of whether or not to walk through those doors.
This isn't an article about aviation barriers, its about business barriers. I want you to consider what are "actual barriers to entry", and not the perceived barrier. So many times we see things like flashy packaging on products; in trade shows we see booths and stacks of guys and gals in suits working the crowd. In chasing federal business you encounter so much complexity in the messaging (e.g. Broad Agency Announcements, Sources Sought Notices, Industry Days ... a lot of messaging.) These all look like barriers.
By now you realize that my message is that none these are actual barriers to entry, but rather perceived barriers to entry. In past years you've probably plowed through similar barriers, but perhaps you never thought of them as barriers. Eventually you find the right way, and the doors open up. Then what would constitute an actual barrier to entry?
Perhaps a strong patent position held by a competitor, or a restrictive access to a market due key technology controlled by competitors. That sounds like an actual barrier to entry. I recently perused the Wikipedia article "https://en.wikipedia.org/wiki/Barriers_to_entry", and if I just restated it here, I'd be wasting your time. The article does a fine job communicating types (legal, less than legal, and economic) of barriers. Its a good read.
In closing, if you're advancing business interests and pursuing opportunity, and you encounter barriers; don't instinctively recoil away from the opportunity because of those barriers. Rather, consider if there are doors that are really open, and you just have to find the right way to walk through those doors.