Shows them you're strong and confident with what you have. When they find out you've got much more they start thinking things like "he said he has a decent job and does okay financially which must mean he's got an amazing job with high income" and other things.
It's not what you have its how you present it and make things work. You could be a millionaire with a horrible outlook and it'll turn women off. You could be living paycheck to paycheck and she'll be turned on by how positive you are.