Showing up at the Chupah without any skills to support your wife financially is like showing up at the start of Succos without a Sukkah or Arba Minim.
The Torah commands men to be fruitful and multiply. The Rabbis specify that it must be with a Jewish marriage and a Kesubah in which the man pledges to financially support the wife and family. If you do not want to make the Kesubah a lie, you must prepare in advance.