This argument that people who say that salvation can be lost are wrong because they are still Christians and so have not lost their salvation is totally illogical.. to the extreme..
Saying that one can fall away from the truth and lose their salvation is not saying that everyone who has salvation will fall away and lose their salvation..
A Christian who believes the Bible and believes that people can lose their salvation does not believe it is so because they have observed someone else lose their salvation or that they have personally lost their salvation.. They believe it because of the scriptures that convince them that a person can discard and renounce the salvation they ones believed and trusted in..
2 Peter 2: KJV
17 These are wells without water, clouds that are carried with a tempest; to whom the mist of darkness is reserved for ever. 18 For when they speak great swelling words of vanity, they allure through the lusts of the flesh, through much wantonness,those that were clean escaped from them who live in error. 19 While they promise them liberty, they themselves are the servants of corruption: for of whom a man is overcome, of the same is he brought in bondage. 20 For if after they have escaped the pollutions of the world through the knowledge of the Lord and Saviour Jesus Christ, they are again entangled therein, and overcome, the latter end is worse with them than the beginning. 21 For it had been better for them not to have known the way of righteousness, than, after they have known it, to turn from the holy commandment delivered unto them. 22 But it is happened unto them according to the true proverb, The dog is turned to his own vomit again; and the sow that was washed to her wallowing in the mire.