If purchasing an oligonucleotide synthesizer is relatively easy, why does KYC still matter?

In recent years, substantial effort has gone into developing Know Your Customer (KYC) frameworks for commercial DNA synthesis providers as a way to reduce catastrophic biological risks.

However, what happens if an individual can simply purchase a DNA synthesizer on the open or secondary (auction) market? In that scenario, KYC requirements imposed on commercial synthesis companies can be bypassed entirely.

If access to DNA synthesizers becomes increasingly accessible, what additional safeguards are needed to mitigate existential or catastrophic biological risks? In particular, what practical and effective measures could be implemented in resource-limited settings where regulatory oversight, infrastructure, and enforcement capacity may be limited?