Thought #1: You're talking about yourself and your wife. Your lifelong partner. So why are you discussing your salary vs. her salary, your savings vs. her savings? My husband and I are a team, and while he's earned more money over the years, I've stretched every dollar for us. Though I work fewer hours, I've put more time and effort into raising the kids. Regardless of what your in-laws say, don't keep score.
Thought #2: Trades are a great option -- for the right person. Given that I'm 4'11" and female, I wouldn't have a chance at your job -- or most other trades, which do require more physical strength than I have ever had, even on my best day. Also, not everyone's going to get those jobs -- only so many exist, and not all trades pay as well as your job. So I'd temper the, "Yeah for trades!" thought process and make it, "Excellent choice for those well-suited to it."
Thought #3: Yes, college is worthwhile financially. The average college graduate is more employable than the average high school graduate, is less likely to experience periods of unemployment, and is more likely to earn a larger paycheck. Certainly you can find examples that disprove this general truth, but overall, a college degree is worthwhile. It's also possible to graduate from college without taking on crushing debt and selling away your future. On a personal note: my children's slightly-older cousins are beginning to graduate from college, and 100% of them are finding jobs in their field, moving out of their parents' houses, and doing all the things you'd expect 20-somethings to do -- looking at them, I am led to believe that the media hype over "college grads can't find jobs" is overblown. Just like everything else, if you're going to college, you need to choose wisely: Choose a degree that'll lead to a job, choose a school that you can afford.
Thought #4: As for your in-laws getting on your nerves, take it as it's meant: They're not trying to insult you -- they're concerned about their little girl. They want to be sure she's well cared for, and they're likely unaware that you're doing so well financially. Personally, I would not clue them into the truth. I'd just make a non-committal, "I'm happy for the moment." Then change the topic. Let them think what they will.