Interesting perspective,according to the Doc,they were lining up to get in, I can see it...

[....Why would anyone volunteer to take an unnamed chemical, even in the interests of medical science and national defense? The intuitive answer might be that nothing short of extortion could induce a rational adult to take such a risk. Surely, only extraordinary and substantial inducements could lure a normal soldier into honoring such a request.

Surprisingly, we never needed to browbeat, threaten or hint at repercussions for someone’s unwillingness to participate in a drug test. Invariably, would-be volunteers inundated us with applications, year after year. An abundance of troops were obviously more than willing to jump through all the hoops required in order to make the list of accepted candidates. In fact, the ratio of the number of applicants to the number accepted increased progressively throughout the 1960's.

If these were “guinea pigs” or (as some writers have referred to them), “unwitting guinea pigs,” one would have to assume that American soldiers in those days lacked basic intelligence. They must have been suffering from personality disorders, or been harboring devious reasons for wanting to take chemicals whose names they might never know, from doctors who could not tell them every detail of the effects to expect. Certainly, they could be perceived as lacking in common sense to take a drug that might deprive them of their mental faculties for up to several days. Undoubtedly, they would want assurances from some independent government agency, such as the Food and Drug Administration, that any chemical they agreed to take was perfectly safe.

How, then, could one explain the fact that between 1955 and 1975, approximately 7,000 healthy enlisted men freely chose to come to Edgewood Arsenal? Each had already met all the Army’s requirements for service, been through the rigors of basic training, and proven his ability to follow the rules of Army life. Yet they came, and all left Edgewood without suffering detectable brain damage or any other serious injury. Furthermore, many of them even requested a second assignment to Edgewood the following year, when the recruiters returned as scheduled to their Army areas.

In 1961, I gave a test dose of the sleeping medication Seconal to a 35-year old career sergeant. He proudly informed me beforehand that this was his sixth visit and he would no doubt be back again next year. I had to tell him that this was unlikely – it would be unfair to all the other soldiers who wanted to be part of the program....]
https://exploringrealhistory.blogspot.com/2018/11/part-2chemical-warfare-secrets-almost.html