Welcome bonuses on gambling websites are indeed real and are commonly offered to attract new players. However, whether you can withdraw the bonus or any winnings derived from it depends on the specific terms and conditions set by the gambling site. Here are some key points to consider:

1. Wagering Requirements
Most welcome bonuses come with wagering requirements, which means you must bet the bonus amount (and sometimes the deposit amount) a certain number of times before you can withdraw any winnings.

For example, if you receive a 100bonus with a 20x wagering requirement, you would need to wager 2,000 before you can withdraw the bonus or any winnings from it.

2. Game Restrictions
Some bonuses may only be used on specific games or types of games. For instance, wagering requirements might only be fulfilled by playing slots, while table games like blackjack or roulette may contribute less or not at all.

3. Time Limits
Welcome bonuses often have a time limit within which you must meet the wagering requirements. If you don’t fulfill the requirements within this period, the bonus and any associated winnings may be forfeited.

4. Maximum Withdrawal Limits
Some bonuses may have a cap on how much you can withdraw from winnings generated using the bonus. Even if you win a large amount, you might only be able to withdraw up to a certain limit.

5. Withdrawal Restrictions
Until you meet the wagering requirements, the bonus and any winnings from it are usually considered "bonus money" and cannot be withdrawn. Only after fulfilling the requirements will the funds be converted to "real money" that can be withdrawn.

6. Bonus Terms and Conditions
Always read the terms and conditions of the welcome bonus carefully. This will outline the specific rules, including wagering requirements, game restrictions, time limits, and withdrawal policies.

7. Realistic Expectations
While it is possible to withdraw welcome bonuses and any winnings, the conditions attached often make it challenging. Many players find it difficult to meet the wagering requirements, especially within the given time frame.

Conclusion:
Welcome bonuses are real, but they come with strings attached. It is possible to withdraw them and any winnings, but only after meeting the specific conditions set by the gambling website. Always read the terms and conditions thoroughly to understand what is required and whether the bonus is worth claiming.