Most people who gamble online lose money over time. That is how the product is built, not bad luck, and a page about bonus codes that does not say so is not being straight with you.
A note specific to bonuses. Chasing a bonus is one of the most reliable ways to deposit more than you intended. A 25x rollover on deposit plus bonus means the money has to go round many times before it is yours, and the people who end up worst off are usually the ones who deposited to reach a bonus tier rather than to play.
Warning signs worth taking seriously: chasing losses with larger stakes; gambling with money set aside for something else; hiding how much or how often you play; borrowing to fund it; and finding that sessions you meant to keep short routinely do not stay short.
Tools that work. Deposit limits are the single most effective control. Set one before your first session, when it is easy, rather than after a bad one. Session reminders and cooling-off periods sit in the same account menu.
Self-exclusion has a gap offshore. A state self-exclusion list does not reach an operator licensed in Curacao. If you are self-excluding, exclude at each offshore operator individually and consider device-level blocking software such as Gamban or BetBlocker, which covers sites you have not thought of.
Free, confidential help. The National Problem Gambling Helpline on 1-800-522-4700 operates 24 hours a day across the United States, by phone and text. Gamblers Anonymous runs meetings in every state. Gam-Anon supports family members, who are often affected first and served last.
If you are reading this because of someone else's gambling, that helpline takes those calls too.