The unspoken word in “Black lives matter” is not “only”–it is not “more”. If there is an implicit modifier in the phrase, it is “also“. If, when you hear the words “black lives matter”, you also assume an unspoken word, such as “more” or “only”, it’s a good idea to ask yourself why.
Please, sit quietly, nonconfrontationally, and completely honestly with yourself and walk through why this is your reaction. Bluntly, and knowing no-one is going to hear your thoughts or judge you for them, honestly learn why you respond to the statement “Black lives matter” as though it were “only Black lives matter” or “Black lives matter more”.
If you get no further than “BUT all lives matter, that’s why ‘black lives matter’ has an unspoken ‘more’ in it”; or if you can’t come up with a better explanation than “I’m not included in the statement ‘black lives matter’, so it must mean ‘only’ “, I’d suggest you need to keep thinking.
“Think”–the strongest admonishment I grew up with. “Why aren’t you thinking?” And “this is not about you”–the best advice I grew up with. These are your guides here, when you ask yourself why you think “Black lives matter” is a threat or an insult to you or why you dismiss it as something that does not concern everyone.