You should do some homework, you'll see how stupid you look. It's not our fault you live under a rock. Valve is back to taking things seriously which means audits of support actions to ensure their work is quality, audit of the steam store to ensure games are within steamworks guidelines. The accounts have no value because the punishments for breaking the ssa are a lot harsher. If you're found to be using an account that is not yours. you're considered a thief and all accounts in your possession are banned. All of Them.. And you're no longer allowed to use Steam at all.
What's left of this market is just people trying to unload who don't give a shit about the buyers to get what they can before they leave this site. Valve gives some level of chance for people to redirect before they just outright ban you from the platform. Get a clue and don't be like the dipshits from forums that are no longer allowed on Steam at all.
Furthermore, no, there's no way to be safe. Having first key DOES NOT MATTER. You use an account that's not made by you, you're done. There's no method to keep these accounts. Whoever says there is, is, a, fucking, liar.
If you wanna test it, link your low digits publicly and let me know if you can unlock them after with your so called master key.
Again, make your own account. Save yourself the stress of lost money. And level up to look cool cause honestly, no one's cared about years of service. The console status in source games days are dead.