If you don’t want negative connotations explain them as unaware : not aware

or conscious; unconscious: to be unaware of any change.

Other possibilities include. Uninformed or incognizant.

What is considered to be a bad investment?

Even a bad investment can be better than the alternative to making no investment at all, if one’s options are limited. In this case, the investor is simply trying to mitigate his or her losses. What are some advantages of investing in a luxury car?

In the example of luxury goods, well, one is most likely investing in more than simple monetary gain. An expensive coat may bring status and / or happiness that would be harder to obtain otherwise.