Afraid that I disagree with you on this one.
I've got no experience of studying Engineering, but I did Psychololgy and Sociology at University and our course had one of the highest drop out rates on campus. Anecdotally, I put this down to two things - firstly, a lot of people took it on expecting to be able to understand their own issues and when it became apparent that it was not going to help them, they dropped out. I also suspect that people found it a lot harder than they expected and subsequently dropped out.
For the record, Psychology often gets labelled as a "soft science" and i believe that people mean that in a dismissive tone, that somehow it doesn't really "count". Really, that is not the case.
Look into some of the areas that Psychology addresses and there is a lot of depth. One of our modules was on Bio-Psychology, looking at neurons and brain mapping. we covered AI and human - computer interaction. We did a lot of work on research methodology as well, including a lot of statistics and Qualitative research... which is extremely hard to do well.
Strangely, i think there is a bit of crossover between a subject like Engineering and Psychology - mainly that they are both trying to understand the operation of complex systems. There are a couple of differences though... not least that with psychology you are stuck using the thing that you are trying to understand. It's a bit like trying to figure out how a car works whils you are driving it. Well, that and the fact that it's harder to take someone's head apart and look inside to see what is going on.
But one thing that you are right about is volunteering for experiments. Milgram got people to voluntarily administer electric shocks of hundreds of volts* to innocent third parties... and all he had to do was ask. I still find that incredible even now.
*(Yes, i know all about the experiment... but it was real to the person giving the shock. Those were the fun days before those damn ethics committies spoiled all the fun...)