Is my friend investing poorly?

[Ben Michel]

Hi guys, I'm new here, and I thought I'd ask your opinion

A friend of mine recently got out of the army, and began buying underpriced properties for cash. Now she owns a couple empty lots, that she plans on holding for a few years, and selling each to a buyer who wish to build a home on. She is brand new to real estate investing, and I feel like the real estate agents took her for a ride

1. Wouldn't investing in a property that would provide rental income be a better solution than just buying a piece of land and hopefully selling it for more in the future?

2. Is buying properties with cash bad idea?

thanks much