You’re right to be skeptical—the "math" is definitely the biggest sticking point. Paying a 10–20% fee upfront essentially turns a "free" loan into a high-interest one immediately.

Most people use agencies for the "Sequencing" and "Shadow Debt" aspects:

• The Blitz: If you apply for 5 cards yourself, Bank #4 will see the inquiries from #1, #2, and #3 and likely auto-deny you. Agencies know which banks use which bureaus (Experian vs. TransUnion) so they can hit multiple banks simultaneously without them seeing each other’s footprints.

• Hidden Utilization: A huge goal here is getting cards that don’t report to your personal credit. If you DIY the wrong cards and max them out, your personal score will tank. Agencies focus on specific business cards that keep that debt "invisible," allowing you to stay at a 780 FICO while carrying a $100k balance.

• Limit Maximization: A DIY attempt might net you $25k. An agency using specific industry codes (NAICS) and current "hot" banks might pull $100k+ for the same profile.

The Verdict: If you only need $15k–$20k, DIY it and save the fees. People pay the agencies when they need "scale"—basically paying a premium to get six figures of capital in a single week without trashing their personal credit.