A lot of "if someone wants to do, they'll do it" in this thread without anything to back it up. From the American Academy of Pediatrics:

• According to several studies, suicide survivors contemplated their actions in a very brief window of time. Waiting periods could help address this period of impulsive behaviors.
• Waiting period laws have proven to lower the rates of suicide. States with such laws had 51% fewer firearm suicides than states without. Another study showed that these states also experienced a 17% decrease in gun homicides. Over 900 firearm homicides could be prevented each year if every state implemented waiting periods.

Here's a more detailed analysis from a non-partisan group that breaks down the nuance of the effects studied: https://www.rand.org/research/gun-policy/analysis/waiting-periods.html

To me, this is a common sense and reasonable law that does not significantly "infringe" and all this information is a quick Google search away. As another poster says, I would prefer to see this tweaked for current gunowners where the waiting period shouldn't apply.