Migrating from On-Premise infrastructure to AWS often results in financial shock due to the shift from CAPEX to OPEX. Treating the cloud as a rented data center leads to 'bill shock' where costs triple unexpectedly. Common pitfalls causing this financial disaster include oversized 'Just in Case' instances, 'Zombie' environments running 24/7, and unattached EBS volumes and Elastic IPs.

Data accumulation in S3 Standard and excessive SQL Server licensing also drive up costs. FinOps is the essential engineering practice to counter this, requiring strict governance, tagging, and AWS Budgets. Developers must understand that inefficient code directly impacts the bottom line. The article advocates for purchasing models like Savings Plans and Spot Instances, and managing LGPD compliance via US East regions.

Ultimately, cloud success requires a cultural shift where engineering decisions are made with financial accountability, preventing the cloud from becoming a financial liability.