Anyone can learn Smart Contract Security for free.
Resources:
@CodeHawks first flights are free
@SoloditOfficial findings are free
@trailofbits publications are free
@CyfrinUpdraft courses are free
@RareSkills_io articles are free
@immunefi write-ups are free
@OpenZeppelin docs are free
@pashov findings are public
@CryptoZombiesHQ is free
@TheSecureum is free
@RektHQ is free
Just learn, practice, and find bugs.