There was definitley a lot of corruption in the USA before Trump. I do think it's also the case that under Trump things got more shameless, and so the administration "dares" to go further.
This is worrisome, especially if you don't think corruption is endemic of the Trump administration. New "boundaries" have been tested and set. Future administrations have a playbook that can allow them to get away with more.
The Trump administration's "astonishing rate of corruption" you are perceiving is being massively overstated by partisan media outlets.
Previous administrations were free to engage in all manners of corruption, while the mainstream media touted their "coolness".