@Akera93 They were planning to build a greenhouse, FOR Venny to put her plants (which are rare plants). They went on a trip to visit the investor (they also mentioned how they found an investor quite fast, which make the marquess suspicious). It's not about how they're adults and have to know that they could die at any moment. They're trying to show their support for Venny (they also ask Venny for her permission first if you read a few chapters back), also the greenhouse could be a successful business for the family, which means they're thinking of Venny's and Daniel's futures too. It's not like they're using the money for gambling or entertainment, or even for their own benefit. It's just an unfortunate accident (or not an accident).
@Elmithian The Marquess is actually an investor for the greenhouse, so I'm sure they're going to pay it back with the profit from the greenhouse. But yeah, the marquess is a bit suspicious, and they should've looked into it before progressing to pay the money.
@AnimefangirlX I'm sure they have their own guards. It might be because the number of the bandits are much more bigger than their own knights (Hugo and Rowell said that they're growing in number recently).