> we are operating under the assumption that freely shared resources can be shared further

Disabuse yourself of this and contact your lawyer ASAP. There is a non-zero chance that the audience of this site shares members with employees and owners of the startups from whom you’ve repurposed these materials.

A cease-and-desist is among the milder responses you can expect, and in the event you are sued you will be compelled to provide a legal response which will mean hiring a litigator.

If you truly are students struggling to pay for your education this an extravagance that your alleged financial situation does not have the means to support.