I was raised as a child in the Presbyterian Denomination, an offshoot of Calvinism. Yet, I never was really exposed to the doctrines. Anyways, I have been a twice born Believer for over 50 years and quite a while ago, rejected Calvinism for the same reasons as you specified. One thing, however, I have also found a person like myself who has hardly any willpower, self control, etc. finds the Holy Spirit can change a person from the inside out when we read the Scriptures that open our eyes to sinful habits of our old nature and to put on Christ, that is, to repent and turn to Him for His resurrection power which establishes the new creation supplanting the old.