The phrase "sticked at nothing" means that someone will do whatever it takes to achieve their goal or desired outcome, regardless of any obstacles or challenges in their way. There are many synonyms that can be used to convey a similar sentiment, such as persistent, determined, unstoppable, unyielding, unrelenting, uncompromising, relentless, and steadfast. All of these words highlight the idea of unwavering commitment and a refusal to give up, no matter the difficulty. Those who stick at nothing are known for their relentless pursuit of success, and these synonyms all capture that same idea in subtly different ways.