No, for several reasons, the banking/monetary transactions being one good one. Another is that some types of computer viruses/trojans actually can get into one computer and get transferred through a network to other computers. Unfortunately I got one of those on my computer. Thankfully we caught it as soon as it showed up and my husband was able to get rid of it, but if it was one that could have not only effected other devices hooked up to the network, but the router and modem as well.
Also if they download large files it will slow your connection down.