I don't see the words, "lose salvation" there. In 1 Timothy 4:1, I presume that you believe "depart from the faith" means that born again believers depart from saving faith in Christ and lose their salvation. The words "the faith" (Greek tês pisteôs) in this context means the apostolic faith, the New Testament apostolic body of doctrines. Some who are in a state of professing adherence to the apostolic faith, nevertheless will in both doctrine and practice depart from it, giving heed to deceiving spirits and doctrines of demons.
Some "nominal" Christians will abandon the faith, the New Testament apostolic body of doctrines for cults or false religions. That does not prove they were previously born again. In 1 John 2:19, we read - They went out from us, but they were not of us; for if they had been of us, they would have continued with us; but they went out that they might be made manifest, that none of them were of us. I believe the beginning of such a departing from the apostolic faith was evidenced as the Roman Catholic church rose to power in the early 4th century. The Roman Catholic church forbids it's clergy to marry. (1 Timothy 4:3) This RCC has other demonic doctrines such as transubstantiation, purgatory, indulgences, works salvation etc..
In 1 Timothy 1:20, we read - Among these are Hymenaeus and Alexander, whom I have handed over to Satan, so that they will be taught not to blaspheme. Where have we heard that before? In 1 Corinthians 5:1-5, we read about a man who has committed sexual immorality by having his father's wife (does that sound like shipwrecked faith? Was it permanent?), yet verse 5 says deliver such a one to Satan for the destruction of the flesh, that his spirit may be saved in the day of the Lord Jesus. If Hymenaeus and Alexander were truly saved, then how do we know the outcome was not the same for them as it was the adulterer in 1 Corinthians 5:1-5 who later repented in 2 Corinthians chapter 2? Nothing is mentioned about him "losing his salvation" either. I don't see the words, "lost salvation" in 1 Timothy 6:10 either, so your argument is INCONCLUSIVE.