No, you cannot simply choose to feed the poor instead of fasting. If you miss fasting during Ramadan, you must make up the missed days by fasting later. This is an obligation and not a personal choice between fasting or paying.
However, if you have a chronic illness or a condition that permanently prevents you from fasting, then you are allowed to feed the poor as compensation (fidya). This applies only to those who are genuinely unable to fast due to medical reasons, not for those who are capable but missed fasting for other reasons.