Yes, the believer who continues to sin and not yield to the Holy Spirit (Rom.6) does suffer eternal loss, not of his salvation, but of his inheritance.
That believer loses the crowns (1Cor.3) he would have had if he had not led a reprobate life ( Rom.14:10,2Cor.5:10)
If you did nothing to earn your salvation (grace) what makes you think that you can do something to lose it? (Eph.2:8-9).
Unless you think have earned your salvation?
Exactly. If Jesus paid for it, who do you think owns it? It is not our salvation to lose.