शतसहस्रादूर्ध्वं राजगामी निधिः ॥ कZ_०४.१.५२ ॥
śatasahasrādūrdhvaṃ rājagāmī nidhiḥ
A treasure exceeding one hundred thousand (in value) shall accrue to the king (i.e., becomes state property).
To centralize extraordinary wealth for state capacity (war, famine relief, administration) while leaving smaller finds partly incentivized for disclosure.