For your consideration ...
Okay, let's get real:
Who carries that kind of cash on them? People engaged in cash-based illegal activity, that's who. Normal people may have a couple hundred cash on them, but not thousands. Not just at the airport, but everywhere. Forget the DEA confiscation part, that's a great way to get robbed by the local talent.
Seriously, draw me a picture of someone who would be carrying large amounts of cash (at the airport, no less) who is on the up and up. I'm willing to change my mind, but I'm not willing to mindlessly jump on a "Oh, these agents are evil!" bandwagon. Government sucks enough, we don't have to make things up.
Devil's advocate here. There is nothing illegal about carrying large amounts of legal tender US currency. In fact, there are many that do not trust banks and keep their money at their home. "Normal people", who are not really normal, but programmed, have been conditioned to not carry large amounts because of the promotion and use of checks, credit cards, and various payment apps, over their lives. The argument for not carrying large amounts because of "drug activity", or one must be into drug dealing or drug use, is a red herring to force people into using traceable and trackable credit card and payment app transactions though digital means.
Your statement, could be construed to mean also that you are also suspect of "normal people" that carries a firearm for self-defense. It could easily be changed to read,
Who carries a concealed firearm with them? People engaged in illegal activity, that's who.
In a free United States, it shouldn't even be questionable when someone carries a large amount of money. It's their business alone. Unless it is proven, through a proper investigation, or as in an illicit activity sting, that the reason the cash is used, is found is to be associated with criminal activity.
Why does someone, anyone, have to prove carrying large amounts of cash is on the "up and up" anyway? Ya see? You too, have been programmed, conditioned, to see nefarious actively absent any real credible and concrete evidence to the contrary, as to the reason no one should have, or have the need, to carry large amounts of money.
These confiscations, absent true cause, have been used solely to instill fear in the public, to change their collective behaviors, to fall in-line with the goal of being able to track every individual's spending habits.
Don't fall for it.