Perils of making a PhD application merely to get funding I know many undergraduate students who are often confused whether to make an MS or PhD application when applying to US universities. They often have the credentials required in a PhD application - good grades, UG-level research, good SOP, etc.

In general, whenever there is a conflict of MS versus PhD, reasonably good students deem it safer to apply for a PhD. While there are lesser positions for PhD, an admit ensures funding and tuition waiver. Later many of those students quit PhD midway and graduate with a master's degree.

What are the risks involved when bachelor's students apply to PhD for purely monetary reasons? Will the tuition waiver cancelled and the students be required to pay the entire fees when they quit? Or do universities bear this loss due to admission decisions that did not work out? Are there any other penalties involved?
It can always happen that a PhD student may not complete, and for a wide variety of reasons, so I doubt that you could actually be prosecuted for fraud for a case like this, unless someone could really prove it.  But realise that whether or not fraud could be proven, such an action could be highly unethical.  Tax payers in your host country would be paying for something they didn't get, and supervisors and administrators would be investing time in someone believing they were likely to become a PhD.  It would be taking away funding from someone, possibly multiple people, who really did want a PhD, both because you would have taken money that could have gone to someone else, but also because in the future, an application similar to yours might not be ranked so well if the admissions board was afraid the outcome might be similar.