The question people ask is which is better. The more useful question is what each one is designed to do, because they solve different halves of the same problem.
Where BPJS is strong
The contribution is small relative to what it covers. There is no medical underwriting, so pre-existing conditions are not excluded. Catastrophic treatment, including dialysis, cardiac care and cancer therapy, sits inside the scheme. For a very large number of families, BPJS is the difference between treatment and no treatment.
Where BPJS hands the problem back
Referral tiers and waiting lists mean time. Your class sets your room and feeds into other tariff limits. Some newer drugs are outside the national formulary. And nothing in the scheme replaces the income you lose while recovering.
What private cover actually buys
Speed and choice: direct admission to a network hospital, a specialist you select, a room above BPJS class. It buys headroom above the point where the national scheme stops. What it does not do is replace BPJS, and dropping BPJS to fund a private policy is rarely a good trade because private cover can be declined, loaded or limited for conditions you already have.
The realistic combination
Keep BPJS as the base that no insurer can take away. Know your employer limit. Then size a private layer around the specific scenario that worries you, usually a private-hospital year plus months without a salary.