It's an expected reaction to XRP, TRX and some other altcoins falling.
People are still mostly trading BTC/Altcoins pair, so moving money from altcoins automatically "boosts" the value of Bitcoin.
That's why I always have at least 50% of my cryptocurrency portfolio in Bitcoin and only invest in well researched altcoins that have a function in real world.
RE: Big Daddy Bitcoin is Back & Your Alts Might be Hurting Because of It