Add a resource of imported goods for stuff from Earth you can't make on Mars. Colonists could start seriously demanding it at a certain population level. For the normal or hard sponsors, this would eat into shuttle capacity and funding.
Make a tourism an industry which can provide funding but can seriously affect funding and applicants if you manage to get tourists killed.
Mars should be more dangerous in general. Considering the quality of the applicants, more people should get themselves killed in accidents or disasters. Add a "hey y'all, watch this!" risk factor to young men. If someone's working a building that suffers a maintenance failure, there should be a risk of injury or death for the workers. Idiots or renegades or otherwise upset should do things that put the dome at risk.
Make a tourism an industry which can provide funding but can seriously affect funding and applicants if you manage to get tourists killed.
Mars should be more dangerous in general. Considering the quality of the applicants, more people should get themselves killed in accidents or disasters. Add a "hey y'all, watch this!" risk factor to young men. If someone's working a building that suffers a maintenance failure, there should be a risk of injury or death for the workers. Idiots or renegades or otherwise upset should do things that put the dome at risk.