How come If statements
 

How come something like this

<if condition="$post[field5] != ''"><center>My Favorite Video Game:</center></if>
<br>
<div align="center">
<if condition="$post[field5] != ''"><img src="images/favgame/$post[field5].png" title="$post[field5]" align="center" border="0"/></if>

Won't work on user profiles?

Because $post is not the variable being used on the profile page. Take a look at the template you are putting the code in and you should see the variable being used.