For this achievement you need to have 65,000,000 studs at hand all at once. This may seem daunting at first but activating multipliers from red bricks makes this rather trivial. You can activate multiple multiplier effects at once which stack to an ultimate multiplier of x3,840
By far the best stage I found for collecting studs is the bonus stage Indominus Rex Pursuit, unlocked through the Jurassic World main missions. Focus on attacking the Gyroball by pressing X, as it will give a handful of blue studs each time you hit it. You should easily be able to get just over 70,000 studs per run (just under a minute) with no multiplier, and activating Stud Attractor will push this up to around 90,000 per run. Adding multipliers will push this into incredible amounts.