My 3-year old son prefers to wear crocs or native only almost all the time. I'm having a hard time convincing him to wear closed shoes especially when we need to attend a semi formal or formal event. Is this normal? Lol

I find this so cute! Yes it is totally normal. Kids tend to have favorite fictional characters, favorite colors, or favorite outfit. This often results to your kids wanting to watch or wear those stuff at all times. I remember back when I was in my grade school, I always choose to wear my favorite jumper even though my mom would require me to be clothed in a dress. Eventually as I grew up, I was cultured to different choices of outfit which made me forget my favorite jumper. I suggest, for now, you take advantage of his crocs and natives. Mold him into his inner model side. Pair his shoes to a formal attire in a way that it will still look classy and stylish.