Deceiving friends for personal gain is unethical and undesirable behavior, which will bring many negative consequences. Relationships between friends based on trust and sincerity are very precious. Deceiving friends will seriously undermine this trust and hurt friends' feelings, which may lead to the breakdown of friendships and make friends feel disappointed, angry and sad. In the long run, this behavior is also not conducive to the development of one's own reputation and interpersonal relationships. Once the deception is discovered, people around them may have a negative view of them, and they may face doubts and alienation from others in social interactions in the future. In any case, you should treat your friends with honesty and integrity, and pursue personal interests through legitimate means, rather than achieving your goals by deceiving friends. Therefore, you must never deceive your friends for personal gain.