Well, the Crouches weren't in any immediate danger. They were a respectable family in the community with a job, hopes and ambitions. The Malfoys had their lives directly threatened for over two years. So, the way I see it, when you're fighting for your basic survival, when you know it's either this or death, you're going to do crazy, desperate things because you don't have anything else left. The Malfoys had their lives at stake, they seemed to helpless for any hopes, ambitions or any thought of the future. It was the present they were fighting for.

The Crouches, OTOH, would have to worry about being discovered (w.r.t to Barty's escape), losing their reputation, going to Azkaban themselves when found out, etc. They had to think of the future consequences before they did anything rash. I just think it's harder to take risks when you're comfortable with a stable livelihood and have hopes and ambitions and dreams. The Malfoys don't have this problem because they see no hope for the future anyway.

So, when I say "less to lose" I mean the Malfoys were much worse off, so desperate actions on their part are easy to visualise.Because they've lost control of their lives: their house is unsafe and invaded, their money is going to procure Voldemort's supplies, they're helpless with no power over their own home, they're being humiliated, losing hope and sanity. All this after Voldemort sent your son on a suicide mission and threatened to kill his parents for over a year. So I wonder why they didn't reach breaking point to take desperate, risky decisions while the Crouches who had none of this could.